.t:LF= EDUCATOR 




Class 




Book 



Gop>TightN^. 



COPYRIGHT DEPOSIIi 



?" -•:- .o^jf;:. V<i»t ^rj^n 



SELF-EDUCATOR 



MARINE AND STATIONARY 
ENGINEERS CATECHISM 



. a , 



PHILADELPHIA 
1915 






Copyright, 1915, by 
WILLIAM C. WILSON 



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,-\^ 

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/-^ ^ 



JUL 3 1915 

^CU406582 



SELFEDUCATOR. 



Rules to Find the Diameter, Circumference 

AND THE x\rEA OF A CiRCLE 

Q. Multiply the square of the diameter by the 
decimal .7854 will give the area. 

Q. How do you square the diameter? 

A. Any diameter multiplied by itself equals 
the diameter squared. For instance, 10 squared 
equals 100. 

Q. Why do you multiply by .7854? 

A. Square the diameter and we get the square 
inches in the square; if we multiply by .7854 we get 
the square inches in the circle, the circle being that 
fraction of the square. 

Q. What do you mean by the word area? 

A. By the area we mean the amount of surface 
exposed to the action of the steam. 

Diameter X by 3.1416 is the circumference of a 
circle. 

Diameter X by .8862 is the side of an equal 
square. 

Diameter X by .7071 is the side of an inscribed 
square. 

Diameter X by .7854 is the area of a circle. 

Radius X by 6.28318 is the circumference. 

Circumference -^ 3.1416 is the diameter. 

The area of a circle -r- by .7854 and extract the 
square root will give the diameter of a circle. 



4 MARINE AND STATIONARY ENGINEERS CATECHISM 



Miscellaneous 

A United States gallon contains 231 cubic inches. 

A United States standard gallon weighs nearly 
8.355 lbs. 

A cubic foot of fresh water weighs 62.5 pounds. 

A cubic foot of sea water weighs 64 pounds. 

35 cubic feet of sea water weigh one ton. 

32 cubic feet of fresh water weigh one ton, and 
weigh 62.5 pounds to a cubic foot. 

2240 pounds weigh one ton. 

A cubic foot of coal weighs 56 pounds. 

5280 feet make one land mile. 

6080 feet make one nautical mile. 

1728 cubic inches make one cubic foot. 

27 cubic feet is one cubic yard. 

144 square inches in one square foot. 

6 feet is one fathom. 

360 degrees is the circumference of a circle. 

7.48 gallons are in a cubic foot. 

To get the circumference use 3.1416. 

1760 yards is one mile. 



MARINE AND STATIONARY ENGINEERS CATECHISM 5 

To Reduce. A Vulgar Fraction to a Decimal 
Fraction 

Divide the numerator of the fraction by the 
denominator, adding ciphers to the numerator 
until it works out in four figures. 

Example: Reduce | to a decimal. 

8)7.0000 (.8750 decimal | 
64 

60 
56 

40 
40 



Again: Reduce | to a decimal. 

8)3. 0000 (.3750 decimal of 
24 



60 
56 

40 
40 



Again: Reduce f to a decimal. 

8)5.0000(.6250 decimal of f 

Again: Reduce j^ to a decimal. 

16)5.0000(.3125 decimal of ^ 

48 

20 
16 



40 
32 

80 
80 



6 MARINE AND STATIONARY ENGINEERS CATECHISM 



Cube Root 

When a number is multiplied by itself twice it is 
called the cube of the number, as the cube of 4 is 
64, because 4X4 = 16 and 16 X 4 = 64, or 4 X 4 X 
4 = 64. The cube root of a number is the number 
the cube of which equals the number. The sign over 
a number expresses the cube of the number. Thus 
53 denotes the cube of 5, = 5 X 5 = 25 X 5 = 125 
or 5 X 5 X 5 = 125 thus ^125 = 5. 



Proportions 

Engineers should be thorough masters of the prin- 
ciples of proportion, as nearly all questions of 
consumption and speed can be solved by it quicker 
than by any other rules. In proportions, if the an- 
swer is to be greater, make the second term the 
greater. As you will notice in the following example, 
the answer was greater because 12 men could earn 
more than 5 men, and if it is to be smaller or less, 
make it the second term. Always let this be your 
guide, for if the answer is to be smaller, make the 
second term the smaller, and if it is to be larger,, 
make the second term the larger. , 



MARINE AND STATIONARY ENGINEERS CATErillSM 7 



Example 



men 

5:12: :30 12 

30 



5)360(72 answer 
35 

10 
10 



If it takes 8 hours to walk 25 miles, how long will 
it take to walk 60 miles at the same gait. The 
answer in this problem is to be greater, so GO miles 
will be the second term. 



25:60:: 8 hours 60 miles 

-. 8 

25)480.0(19.2 
25 

230 
225 

50 
50 



If the repairs to an engine take 9 men 18 days 

to do a job, how long will 16 men take to do it. 

The answer is to be smaller, as 16 men will do the 

work in less time, so we make 9 men the second term : 

16:9: : 18 = 10 days. 

18 
9 

16)162(10 days 
16 



8 MARINE AND STATIONARY ENGINEERS CATECHISM 



Square Root 

When a number is multiplied by itself it is said 
to be squared, and is called the square of the number. 
As 8 X 8 = 64 is the square of 8, the square root 
of any number is the number whose square is equal 
to the number given. The square root of any 
number up to one hundred may easily be found 
without working out, as the square root of 36 is 
6 because 6 X 6 = 36 again ^^81 = 9; ^^100 = 10. 
To get the square root of a large number, proceed 
as follows: write down the number that the square 
root has to be extracted from. Mark two figures, 
counting from the right to the left in whole numbers, 
and from the decimal point to the right point off 
every two figures to the left. To get the square root 
of 622521: 



62|25121(789 answer 

49 Get the square root of 

148)1325 31|83|00(5.64 answer 

1184 25 



1569)14121 106)683 

14121 636 



1124)4700 
4496 



Get the square root 1 144(12 answer 
1 

22)044 
44 



MARINE AND STATIONARY ENGINEERS CATECHISM 9 



Practical Questions 

Q. What type of boilers are mostly used for marine 
work? 

A. The Scotch boiler on land vessels and tugs. 

Q. What boilers are mostly used on land? 

A. The return tubular boiler set in brickwork. 

Q. Name the important parts to be looked after 
on a boiler. Leaving out for the present the ques- 
tion of whether the boiler was properly designed 
originally. 

A. The exterior of the boiler should be examined 
for corrosion, expecially at the fire line and around 
the ash pits if it is surrounded by water space. The 
surface exposed to the fire should be examined for 
blisters, and if any appear they should be cut with 
a chisel so that their depth and extent should be 
known. 

Q. Have you noticed any scale on flues or crown 
sheets? If you did how would you remove it? 

A. By using compound. 

Q. How is the pitch or the distance found between 
the rivet holes in a boiler plate? 

A. Divide the area of the hole by the thickness 
of the plate and add the diameter of one hole. 

Q. What is the effect of using steam expansively? 

A. Its effect is in the economy due to the use of 
the expanding of steam below the boiler pressure. 

Q. What is meant by sensible heat and latent 
heat? 



10 MARINE AND STATIONARY ENGINEERS CATECHISM 

A. Sensible heat is that required to raise the tem- 
perature of water from freezing point to the tempera- 
ture of steam. Latent heat is that required to evap- 
orate the water at the given temperature or the 
heat which disappears in effecting the converting 
of water into vapor. 

Q. Have you noticed any bulging in the fire-box 
plates? If you found a thin place in your boiler 
what would you do? 

A. Put a patch on it. 

Q. Would you put a patch on the outside? 

A. No; put it on the inside. 

Q. Why so? 

A. Because the action that has weakened the 
plate will then act on the patch, and when this is 
worn it can be replaced; but the plate remains 
as we found it if the patch were put on the outside. 
The action would still be on the patch, which would 
in time be worn through, then the pressure of steam 
would force the water between the plate and the 
patch, and so corrode it, and during an extra pressure 
the patch might blow off. 

Q. If you found several thin plates what would 
you do? 

A. Patch each one and reduce the steam pressure. 

Q. If you found a blistered plate what would you 
do? 

A. Put a patch on the fire side of the boiler. 

Q. If you found a plate at the bottom buckled? 

A. Put a stay through the centre of the buckle. 

Q. If you found several buckles? 



MARINE AND STATIONARY ENGINEERS CATECHISM 11 

A. Stay each one and reduce the steam pressure. 

Q. If the crown of a furnace were down, what 
then? 

A. Jack it up or put a bolt through the middle 
and a dog across the top if the furnace were dowm. 
Lengthwise, put a series of bolts and dogs. 

Q. If you had a crack, what would you do? 

A. Drill a hole at each end of the crack, calk the 
crack or put a patch over it. 

Q. If the water in the boiler is allowed to get too 
low what may be the consequence? 

A. Burn the top of the combusting chamber and 
the tubes, and perhaps cause an explosion. 

Q. If the water were to get too high in the boiler 
what then? 

A. It would cause priming and maybe cause the 
cylinder head to break. 

Q. What would you do in case the boiler was to 
foam and carry the water over in the engine? 

A. Open my surface flow^ and slow dow^n my 
engine. 

Q. How would you line up an engine? 

A. Remove all parts except the cylinder and 
crank shaft, strike a line from the top of the cylinder 
head to the bottom of the crank pit, put the engine 
on top centre, take the centre of the crank pin, take 
the centre of the top of the cylinder, the centre of the 
bottom of the stuffing box, then put the engine 
on the bottom centre, and if you find it comes the 
same your engine is in line. Then line your 
guides. 



12 MARINE AND STATIONARY ENGINEERS CATECHISM 

Q. Where is most pressure on a flat-bottom boiler? 

A. On the bottom with the steam pressure and 
weight of the water. 

Q. What is the difference between a high-pressure 
engine and a low-pressure engine? 

A. The high-pressure engine exhausts against 
15 pounds of the atmospheric pressure while the 
low-pressure engine exhausts in a condenser with an 
air pump attached which relieves that pressure. 

Q. What is vacuum? 

A. It is a space avoided of all pressure. 

Q. How would you place the cams on a shaft? 

A. Ninety degrees ahead of the crank or J diameter. 

Q. How would you set cut-off valves? 

A. Place the engine on the top centre, place the 
valves on the cut-off stem, run the valves up until 
they cover the top and bottom port, then the valve 
is square; then pry the engine down to where you 
want to cut-off, run your cut-off valves up until 
they cover the ports, and so on to balance the 
stroke. 

Q. How would you set main valve of an engine? 

A. Place the engine on the top centre, put the 
links in the head motion, give the valve the proper 
lead, then reverse the links in the backing motion 
on the same centre, and if the lead is the same, the 
valve is square; place the engine on the bottom 
centre and do the same and the valve is set. 

Q. How far is the bottom gauge cock above the 
crown sheet or tubes in the boiler? 

A. From four to five inches. 



MARINE AND STATIONARY ENGINEERS CATECHISM 13 

Q. How do you determine the tensile strength 
of a boiler? 

A. Tensile strength of a boiler plate means the 
resistance which a piece of metal offers to being 
torn asunder in the direction of the line of fiber; 
for instance, when we say that a certain boiler 
plate has tensile strength of 50,000 pounds we mean 
that it takes 50,000 pounds of force or weight to 
tear asunder, or entirely separate, a piece of metal 
just one inch square of section. There are certain 
methods by which tensile strength and ductility 
are found, and, furthermore, there are certain 
methods which each bear toward the other, which 
is important for engineers to know. Let us look 
into this for a few moments. In regard to deter- 
mining the tensile strength of a strip of the plate 
cut from a boiler to be tested, it is cut off to a certain 
length and width, and is governed by the thickness 
of the plate. It is not the intention here to go into 
minor details. In determining the tensile strength 
the strip is carefully measured in all directions and 
the result noted after it is placed in a testing machine 
and subjected to a force sufficient to break asunder, 
such force being recorded by the machine ; then the 
calculations are made in the following manner. 
Let us assume that we have a test piece which at 
the point where the fracture is to take place, is ^ 
inch wide and J inch thick. Now to find the area, 
as per requirements of the foregoing rule, we must 
multiply the wddth by the thickness, which is 
.5 X .5 = .25 area at point of fracture. Let us also 



14 MARINE AND STATIONARY ENGINEERS CATECHISM 

assume that the strain at which our test piece parted 
is 15,000 pounds, therefore 15,000 -^ .5 X .5 = 
60,000 pounds tensile strength per square inch. 



J 



l-2x1-2iN. 



Half inch thick half inch wide. 

.25)15,000.00(60,000 tensile strength 
150 



What Advantage Does Steel Have Over Iron? 

First, it is Hghter; second, it is stronger; third, 
its condensing power is higher; for instance, it will 
evaporate 25 per cent, more water with the same 
amount of fuel in a given time. Steel boilers are 
more free from corrosion than iron on account 
of the density and compactness of the material. 

Construction of a steam gauge. 

The principle of a dial steam gauge is that the 
pressure may be indicated by means of a pointer 
in a divided dial similar to a clock face, but marked 
in division, indicating pound pressure per square 
inch above the atmospheric pressure, and shows 
the ordinary style of gauge, which consists of an 
elliptical tube connected at one end to a steam pipe 
in connection with the boiler pressure. 

Q. What causes pitting in a boiler? 

A. An acid which generally comes from animal oil. 



MARINE AND STATIONARY ENGINEERS CATECHISM 15 

Q. How should pitting in a boiler be treated? 

A. First it should be scraped and cleaned with a 
strong solution of soda or coal oil to remove grease 
and acids and then covered with a thin coat of white 
zinc to fill up the pit holes to prevent further pitting. 

Q. What benefit is derived from circulation of 
the water in a Scotch boiler when the engine is 
stopped ? 

A. The boiler is kept at a more equal tempera- 
ture, and contraction and expansion is not so great. 

Q. Where is the most pressure on a boiler and 
why? 

A. A boiler when filled with water, and when it 
has a steam pressure, contains the most at the 
bottom, because the bottom has the weight of the 
water plus the pressure of steam. 

Q. What should be done if a boiler head were to 
crack from one tube to the other? 

A. One or more holes should be drilled into the 
crack and tapped out, and in those holes, plugs 
should be screwed and tapped and calked. 

Q. Where would you look for pitting in a sta- 
tionary boiler? 

A. ^lost generally on the tubes, and sometimes 
pitting takes place on the water line or a little below. 

Q. Where would you look for pitting in a marine 
boiler? 

A. The fire line of the furnace, also around the 
combustion chamber, and the back head and in some 
Scotch boilers it is known to pit on the bottom of 
the boiler. 



16 MARINE AND STATIONARY ENGINEERS CATECHISM 

Q. In what direction is the steam pressure in a 
boiler exerted? 

A. In all directions. 

Q. Why is the butt joint of a boiler the strongest? 

A. The butt joint is the strongest because it is 
a true circle. 

Q. Why are the short screw stay bolts turned 
smooth in the centre? 

A. They are turned smooth in the centre to pre- 
vent corrosion, as a smooth surface does not corrode 
as quickly as it does in rough stays. 

Q. Why is a large factor of safety used for boiler 
stays? 

A. A large factor of safety is used to allow for 
corrosion or eating away of the metal. 

Q. What are the four principal points to consider 
in cylinder boilers for carrying high steam pressure? 

A. First, the tensile strength; second, diameter; 
third, pitch and size of rivet; fourth, thickness of 
plate. 

Q. Will a boiler 72 inches in diameter f thick 
made of iron stand as much pressure as a boiler 
48 inches in diameter and | thick? 

A. No. 

Q. Why? 

A. Because the pressure in a large boiler has 
more surface and will not allow it. It is the same 
as a long bar of the same thickness. It takes less 
to break the small one than the short one. 

Q. How do you ascertain if your shaft is out of 
line? 



MARINE AND STATIONARY ENGINEERS CATECHISM 17 

A. Take the coupling bolts out of the coupling, 
and if the coupling faces up square the shaft is in 
line. 

Q. How is it arranged sometimes to give a boiler 
more power? 

A. By using a forced draft. 

Explain the Thermometer 

A thermometer is based on the change of volume 
to which bodies are subject with the change of 
temperature. A thermometer is filled with air, 
water, or mercury. It consists of a tube of glass 
formed with a bulb at the bottom filled with mer- 
cury, and it is graduated in numbers: blood heat, 
100°; temperature, 52°; freezing, 32°. Boiling- 
point is divided into 180°, freezing being 32° and 
boiling 212°. 

Q. Name the different kinds of compound engines ? 

A. Tandem cross, high-pressure, low-pressure, 
triple expansion, and quadruple expansion. 

Q. How much larger is the low-pressure cylinder 
than the high-pressure cylinder? 

A. Twice the area of the high-pressure cylinder. 

Q. How is the horse power of a non-condensing 
compound engine found? 

A. By finding the area of each cylinder separately, 
then adding them together and dividing by two to 
get the average. Then the mean effective pressure 
is found by adding the two mean effective pressures 
together and divide by two less the back pressure. 



18 MARINE AND STATIONARY ENGINEERS CATECHISM 

Q. What is a surface condenser? 

A. It is where the exhaust steam flows around 
cold tubes that the circulating water passes through 
condenses the steam into water. It drops to the 
bottom of the condenser, is then taken out by an 
air pump and pumped back to the boiler. 

What is a Jet Condenser 

A. It is a chamber in which the exhaust is com- 
pelled to pass through a spray or a jet of cold water, 
and after condensed it mixes with the injection 
water into a hot well and from there some is pumped 
in the boiler and the balance is pumped overboard. 

Q. Which is the most economical of the two, a 
jet or a surface condenser? 

A. The jet for stationary work, because it uses 
less water. 

Corliss Engine 

Q. How is a Corliss engine valve set and adjusted? 

A. First take ofi^ the back caps of all four valve 
chambers. Lines will be found on the end of the 
chambers which show the working edge of the ports 
and valves and the lap and lead. The wrist plate 
central located between the four valves has three 
lines on top of its hub edge, and correspond with 
the single lines on top of the brackets. They show 
the central and two positions of four valves. The 
valve is next adjusted by unhooking the reach rod 
from the wrist-plate pin, then hold the wrist plate 



MARINE AND STATIONARY ENGINEERS CATECHISM 19 

in the central position, and by means of right and 
left thread rods, adjust each valve singly. Set the 
steam so they will have J inch lap for a 10-inch 
cylinder and J-inch lap for 32-inch cylinder. Ex- 
haust valves should have yV lap for 10-inch cylinder, 
I for 32-inch cylinder. For high-pressure no lap- 
condensing engine gives nearly double the lap. 

Q. After making those adjustments what is to 
be done? 

A. The dash pot rods are adjusted by turning 
the wrist plate to its extreme of travel and adjust 
each rod so that when the rod is down as far as it 
will go the stud on the valve arm will just clear the 
latch on the latch hook. 

Q. If the rod is too long or too short what is to 
be done? 

A. If the rod is too short the hook will not drop 
in; the valve will not open. 

Q. How much salt would you allow the water to 
get in a boiler with a jet condenser and surface con- 
denser? 

A. Not over li to 3%. 

Salinometer 

A salinometer is a glass or a metal instrument 
by which the density of water is ascertained. It 
consists of a weighted bulb, to which is attached 
graduated steam, and its action is to indicate the 
amount of salt held in solution in the water by 
floating higher or lower — higher for density and 



20 MAKINE AND STATIONARY ENGINEERS CATECHISM 

lower for freshness. Some are graduated into 33 
rods and some to 32 rods, each representing about 
five ounces of salt to a gallon of water. Care must 
be taken to use the salinometer at the temperature 
for which it is marked, as the density of fluids vary 
in proportion to their temperature, 200° being the 
usual temperature of the water in which these 
instruments are tested, so that they may be used 
almost immediately on the water from the boiler. 

Sea water contains ^V part salt — that is, if 32 
pounds of sea water were evaporated one pound 
of salt would remain. ^V is for this reason taken 
as the unit by which to measure the density of the 
boiler water. If the water in the boiler has the same 
amount of salt in it as sea water, we say it has one 
degree of salt; if it contains twice as much salt per 
gallon as sea water, then it has two degrees of salt 
— that is, ^% salt; five ounces of salt to a gallon. 
Do not let the water in the boiler get over 1 J or -^ 
salt in the boiler. 

Q. Could you make a salinometer if you had 
none? 

A. Yes; take a bottle and weight it down so 
it will fioat upright, then take some fresh water 
and put it on some hot coal and boil it to 190° or 
200°, then place the bottle in the fresh water and 
mark the bottle at the fresh water line; then take 
some salt water out of the sea and boil it 190° or 
200°; then you will find the bottle will raise -j^, the 
difference between fresh water and salt water. 



MARINE AND STATIONARY ENGINEERS CATECHISM 21 



Indicator 

Q. What is the use of an indicator on an engine 
and what information does it give? 

A. It shows the expansion of steam in the cylinder, 
also if the valves are properly set and adjusted. 

Q. How many lines does the indicator card show 
when steam is against the indicator piston, also 
when turned off? 

A. Seven lines: six with steam — namely, compres- 
sion, admission, steam, expansion, release, and 
exhaust. 

Q. When steam is turned off the indicator, the 
atmosphere line is drawn, making the seven, are 
there any other lines drawn on the card, and if so, 
when? 

A. Yes, two, the vacuum and clearance lines. 
They are drawn after the card has been laid out on 
a flat surface board. 

Q. How are cards measured and calculated to 
find the M. E. P.? 

A. By dividing the length of the card into 10 
equal parts by drawing perpendicular lines in regular 
order called ordinates from the steam end to expan- 
sion line down to the atmosphere line. 

Q. After the card has been properly laid out 
what should be done? 

A. Take a strip of paper | inch wide and about 
12 inches long. Lay it alongside of the first ordi- 
nate, mark the length, then lay the strip up to the 



22 MARINE AND STATIONARY ENGINEERS CATECHISM 

second ordinate so its length will be added to the 
first, and so on until all the 10 ordinates will be in 
one straight line. Then take total measurement 
in inches. Suppose the total length w^as 9 inches 
long and the spring was 30 pounds, how is the 
M. E. P. found? 

A. The card is 9 inches long X by the spring 
30 pounds divided by 10 ordinate. 



30 spring 
9 length of card 

ordinate 10)270(27 mean effective pressure 
20 



70 
70 



Q. What is meant by M. E. P.? 

A. It is the mean effective pressure of steam that 
is on the piston throughout the stroke less the 
back pressure. 

Q. How is the horse power of an engine found 
when the M. E. P. is known? 

A. Find the area of piston X by M. E. P. X by 
piston speed in feet per minute and divide by 
33,000. This equals the horse-power. 

A. Diameter of cylinder, 20 inches; stroke of 
engine, 20 inches; mean effective pressure on piston, 
27 pounds; revolutions per minute, 120. 



MARINE AND STATIONARY ENGINEERS CATECHISM 23 



Example to Find the Horse-Power 



20 in. stroke 20 diameter of cylinder 

20 20 

40 inches 400 

120 revolution 
.7854 

800 400 

40 

314 . 1600 area of piston 

12)4800(400 feet per minute 27 M. E. pressure 

48 



21991200 
6283200 



8482.3200 

400 feet per minute 



33000)3392928 . 0000(102 . 8 horse-power 
33 



92 
66 



269 

264 



Another Way to Get the Horse-Power 

To get the horse-power of indicator card, first 
get the square inches in the cyHnder, then mul- 
tiply that by .7854 to get the area, then multiply 
the area by twice the stroke in feet multiplied by 
revolution and divide by 33,000; that will give the 
constant; then count the card up to get the M. E. P. 
We will say the M. E. P. is 40 on the piston. Mul- 
tiply half the card by the constant, half the card is 
20 pounds, that will give the horse-power of the 



24 MARINE AND STATIONARY ENGINEERS CATECHISM 

engine and deduct the atmospheric pressure from 
the horse-power. We will take the diameter of the 
cylinder 18 inches, 18-inch stroke 100 revolutions 
per minute, allowing 33,000 pounds per horse-power. 



Example 



18 stroke of engine 

18 

36 
100 revolution 

12)3600(300 feet 
36 



18 diameter cylinder 

18 

144 

18 

324 square of cylinder 

.7854- 
324 



31416 
15708 
23562 




254.4696 

300 feet per minute 


33,000)76340.8800(2.31 constant 
66000 


103408 
99000 


2.31 constant 
20 half card 


44088 
33000 


46.20 



This example is to get the M. E. P. of card on 
piston mean effective pressure on piston 40. 

Horse power is 46.20. 

Q. If at sea and the water in the boiler was gaining 
where would you look for the trouble and what 
would vou do? 



MARINE AND STATIONARY ENGINEERS CATECHISM 25 

A. Try the water in the filter box or hot well for 
salt, if I found the water salt I would try all valves 
that were attached to the condenser from the sea, 
if I found them all right I would see if the discharge 
from the air pump was taking in water as it some- 
times does when a ship is rolling deep and if the 
water still continues to gain in the boiler I would 
give each boiler a little blow and when in port take 
off condenser heads and plug tubes. 

Q. Why is too late admission loss of power? 

A. Too late admission is a loss of power because 
the piston has travelled a part of the stroke before 
the steam has attained to its full pressure. Late 
admission means that the valve has no lead. 

Q. If the high pressure of a compound engine 
was on the centre, how would you start it? 

A. Admit steam to the low pressure cylinder. 

Q. How much lap should a piston valve 
have? 

A. About the same as a slide valve has. 

Q. Which will have the most lap exhaust or piston 
valve? 

A. There is not any difference. 

Q. From which end of the cylinder does the piston 
travel the faster? 

A. It always travels the faster on leaving the 
head end of the cylinder on account of the weight 
of the connecting rod and piston. 

Q. How would you run a tandem compound 
engine if either high or low valve stem should 
break? 



2G MARINE AND STATIONARY ENGINEERS CATECHISM 

A. If high valve stem should break, take out 
the valve and run with a reduced boiler pressure; 
if the low valve stem should break, take out the 
valve and run as a simple. 

Q. If a crank broke on the high pressure side of 
a cross compound engine how would you run it? 

A. Take out valve, block piston and crank, and 
run with a reduced pressure. 

Q. How would you run if crank broke on low 
pressure side? 

A. Take out low-pressure valve, block the piston 
at its crank, and run as above. 

Q. How would you set the valves on a Corliss 
engine to run high pressure? 

A. Set the steam valves with f of an inch lap; 
exhaust valve line and line when the wrist plate 
was central and hook in, and make further adjust- 
ment with the indicator. 

Q. How would you set them to run on a condenser? 

A. With a little more lead and a little earlier 
compression. 

Q. What advantage do we get in having an eccen- 
tric on a Corliss engine? 

A. Greater range of cut off. 

Q. Should there be two wrist plates? 

A. It's not necessary. 

Q. Why do we give more lap on the steam valve 
of a large Corliss engine than we do to the small one? 

A. To get earlier compression. 

Q. How would you give a Corliss engine more 
lead without giving it more compression? 



MARINE AND STATIONARY ENGINEERS CATECHISM Z / 

A. Shorten the steam hnk. 

Q. How would you give Corhss engine more 
compression? 

A. Advance the eccentric, making the required 
change or lengthening steam links. 

Q. Does the eccentric set ahead or behind the 
crank of an automatic engine and why? 

A. If the engine is to run ahead, the eccentric 
sets behind the crank, because it is a direct 
motion with the piston and indirect from the 
governor. 

Q. What is a cross compound engine? 

A. One in which the cylinders set side by side and 
with cranks usually at right angles to each crank. 

Q. What is a tandem compound engine? 

A. One in which one cylinder seats ahead of the 
other on the same piston rod and connected to the 
same crank. 

Q. Why is a compound engine more economical 
than a simple engine, when the steam pressure is the 
same? 

A. Smaller ports and less condensation. 

Q. If you were at sea and your high-pressure 
engine became disabled beyond repairs, how would 
you proceed? 

A. Disconnect your high-pressure engine and run 
with your after engine. 

Q. Describe just what you would do upon enter- 
ing your engine room in the morning, the plant 
being shut down under fires banked through the 
night? 



28 MARINE AND STATIONARY ENGINEERS CATECHISM 

A. The first duty of an engineer when entering 
his plant at any time is to ascertain how the water 
in the boiler stands; he should open the gauge 
cocks and note what came from each in turn, then 
open the cocks or valves connected to the water 
glass gauge, and note the water line there shown; 
he should also blow the water column out in case 
any sediment may have choked any of the passage 
which would be liable to give a false impression 
as to the actual quantity of water contained in the 
boiler. Should the water be found at the correct 
height, he may now proceed tohaulhis fires down; then 
when the boiler has made about 25 or 30 pounds of 
steam, you should give your boiler a good blow down. 

Q. How would you find travel of a valve having 
a steam lap of f of an inch and a maximum port 
opening of If inches? 

A. The maximum port opening at the head end 
plus the lap at the head plus lap at the crank end 
11 + 11 + 4 + 1 = 4i the required travel of the 
valve. It is well to give practical methods. The 
travel of any valve is obtained from the eccentric 
by subtracting the thin part of the eccentric from 
the thick part of the eccentric, is termed the throw 
of the eccentric. 

Q. Can a proper vacuum be formed? 

A. No, about 9 to 11 per cent, of the atmospheric 
pressure, which is 14.7 pounds per square inch. 

Q. What will vacuum do? 

A. It will raise water 33 feet, providing all pipes 
and connections are air-tight. 



MARINE AND STATIONARY ENGINEERS CATECHISM 29 

Q. Name the different things that will affect the 
vacuum in a condenser. 

A. Extra feed valves being open after tank is 
empty, circulating pump running too slow, condenser 
being too small, dirty tubes, low-pressure piston 
packing too loose in stuffing-box, air-pump valves 
or piston packing bad, or any leak that will admit 
air in condenser. 

Q. If you were compelled to change from 
surface to a jet condenser, how would you 
proceed? 

A. Stop circulating pump if it is working; start 
the engine and open the jet valve on condenser 
slowly, until I have it open enough to form twenty 
inches of vacuum or more. 

Q. What would be the result if you opened the 
jet valve too much? 

A. You would admit too much water to the con- 
denser, therefore cutting too much load on the air- 
pump. 

Q. If you were running jet condenser and you 
stopped, what would you do? 

A. Shut off the injection valve to condenser. 

Q. Why would you shut off injection valve to 
condenser? 

A. To hold the vacuum in the condenser as long 
as possible and not to flood the condenser. 

Q. Explain how shutting off injection valve on 
the condenser w^ould hold the vacuum? 

A. As vacuum is a space void of all pressure and 
you leave any valve open that will admit air or 



30 MARINE AND STATIONARY ENGINEERS CATECHISM 

water, you will have atmosphere or water pressure 
in your condenser. 

Q. If you had atmosphere or water pressure in 
your condenser how would it effect the engine 
starting? 

A. It would cause the engine to start bad, and put 
on extra load on the air-pump and discharge pipe; 
it has been known to cause a break down. 

Q. Why is a condenser used? 

A. To relieve the engine of back pressure and 
maintain fresh water for the boiler. 

Q. If you were at sea and your circulation pump 
became disabled, how would you get into port? 

A. Run jet condenser; if not, run high-pressure. 

Q. If your air-pump were to break down and you 
had no other pump to take its place, what would 
you do? 

A. Keep the circulation pump running, take 
oft' bottom plates on condenser, let the condensed 
water run in the bilge, and pump it out. 

Q. If you had no water jet on your condenser, 
how would you make a jet condenser out of a sur- 
face condenser? 

A. By taking out enough tubes to supply the 
condenser with water to condense steam and use 
the sea cock for the jet valve. 

Q. Why will a pump refuse to lift hot water? 

A. A pump will refuse to lift hot water because 
the vapor will rise and prevent a vacuum from being 
formed, and consequently an unbalanced condition 
of pressure cannot exist which is necessary to cause 



MARINE AND STATIONARY ENGINEERS CATECHISM 31 

the water to flow up to the pump, therefore if you 
want to pump hot water place the pump so that the 
hot water will run to it. 



Evaporation of Water and Coal Burn 

Q. How many pounds of water would you expect 
a pound of coal to evaporate, and how many pounds 
of water required per hour for triple expansion 
engine? 

A. A good boiler will evaporate ten pounds of 
water under ordinary circumstances, but it depends 
upon the efficiency of the boiler, the quality of coal, 
the temperature of the feed water and the tempera- 
ture of which steam is generated. A triple expan- 
sion engine requires eleven or twelve pounds of 
water per hour. 

Q. How much water will a pound of coal evaporate ? 

A. The average is about one gallon per pound of 
coal. 

Q. What is the consumption of coal per square 
foot of grate surface in a steam boiler? 

A. With natural draft about ten to twelve pounds 
per square foot of grate surface. 

Q. What is the water consumption in pounds 
per hour indicated horse power? 

A. From 25 pounds to 60 pounds. 

Q. What is lead on a valve? 

A. Lead is the distance or amount that the valve 
comes short of covering the port when the piston is 
at the beginning of the stroke. 



32 MARINE AND STATIONARY ENGINEERS CATECHISM 

Q. How many kinds of lead are there? 

A. There are two kmds outside or steam lead 
and inside or exhaust lead, outside or steam lead is 
the distance that the outside or steam side edge of 
the valve comes short of covering the port when 
the piston is at the beginning of the stroke, inside or 
exhaust side edge of the valve comes short of cover- 
ing the port when the piston is at beginning of the 
stroke. 

Q. How do you give an engine more lead? 

A. By advancing the eccentric on the shaft. 

Q. What effect has too much lead on an engine? 

A. It causes the engine to pound also forms too 
much cushioning. 

Q. What is the use of lap on a valve? 

A. Give the engine compression and also to work 
the steam expansively. 

Q. What is the use of a valve? 

A. It regulates the flow of steam to and from 
cylinder. 

Q. What use is a link on an engine? 

A. To cut off the steam at different parts of stroke. 

Q. How much heating surface is allowed per 
horse-power in a boiler? 

A. Twelve to fifteen square feet. 

Q. How do you find the proper size of a safety 
valve to be placed on a boiler? 

A. Three square feet of grate surface is allowed 
for one inch of area of valve. 

Q. How hot can you get water under atmospheric 
pressure with exhaust steam? 



MARINE AND STATIONARY ENGINEERS CATECHISM 33 

A. 212 degrees. 

Q. What is meant by atmospheric pressure? 

A. The weight of the atmosphere. 

Q. What is the weight of the atmospheric pressure 
at the sea level? 

A. 14.7 pounds. 

Q. How many pounds of water can be evaporated 
with one pound of the best soft coal? 

A. From 7 to 10 pounds. 

Q. W'hy do we condense steam? 

A. To form a vacuum and so destroy the back 
pressure that would otherwise be on the piston and 
thus get more useful work out of the steam. 

Q. W'hat is meant by horse-power? 

A. Horse-power is equivalent to raising 33,000 
pounds one foot high per minute. 

Q. What is meant by a triple expansion engine? 

A. A triple expansion engine has three cylinders 
using the steam expansively in each cylinder. 

Q. What is meant by using steam expansively? 

A. When the steam is admitted at a certain 
pressure, is cut off, and allowed to expand to a lower 
pressure. 

Q. What would you do if you were to knock your 
top cylinder head out of your compound engine 
beyond repairs? 

A. Block the steam ports so as not to admit 
any steam on the top end of the piston, reduce 
steam pressure and proceed. If it sticks on the centre 
put a liner under the eccentric rod so as to admit 
more steam on the bottom of the piston. 



34 MARINE AND STATIONARY ENGINEERS CATECHISM 

Q. What would you do if you broke a low pres- 
sure connecting rod on compound engine? 

A. Use the high-pressure connecting rod and put 
it in the low, then take high-pressure vailve out, 
so as to let steam pass over into the low-pressure 
valve, then let the high-pressure piston down to the 
bottom of the cylinder, then reduce steam pressure. 

Q. What is the object of putting zinc plates in a 
boiler? 

A. It causes a galvanic action and the acids in 
the water act directly in the zinc plates instead of 
on the boiler plates and shell. 

Q. How often should the zinc plates be renewed? 

A. As often as they are corroded and eaten away. 

Q. To find the scale of the spring for taking a 
diagram from high-pressure cylinder? 

A. Divide the gauge pressure by 2i. 

Q. In a triple-expansion engine with second 
cylinder doing much more work than low pressure, 
how can your cut off be best adjusted in either cylin- 
ders to balance load between cylinders? 

A. By shortening the cut off on the low^-pressure 
cylinder t lus increasing the back pressure on inter- 
mediate reducing the pressure on it, also the back 
pressure on the high-pressure cylinder. 

Q. What is the effect on receiver pressure of 
cutting off later in first cylinder? 

A. The receiver pressure will be raised and the 
engine will perform more work. Tie low pressure 
piston in this case will perform more work than the 
high pressure piston on the former. The pressure 



MARINE AND STATIONARY ENGINEERS CATECHISM 35 

is increased, while on the latter the back pressure, 
the cut off, and has to be regulated for both cylinders 
to make them perform even share of the work. 

Q. Name the bad features of the keel condenser? 

A. Two bad features of the keel condenser are 
that the water will not flow good to the air pump, 
and if the climate is cold enough to bring the water 
on the outside of the condenser down to a freezing 
point the fresh water in the condenser will freeze 
solid, and that will be an extra expense. 

Q. Can the heat of steam be raised to a very 
high temperature? 

A. Steam can be heated to nearly a red heat, 
but not while it is held in contact with water. 

Q. How is it arranged sometimes to give a boiler 
more power? 

A. By using forced draft. 

Q. Are holes drilled or punched in a boiler? 

A. They are drilled in a boiler. 

Q. What would be the result of incorrect length 
of eccentric rod? 

A. Too much lead on the rod or not enough lead. 

Q. The question is very often asked why they 
use a piston valve? 

A. You take a 10 inch piston valve, the area is 
78 inches with 120 pounds of steam would be 78 
inches X by 120 = 93.60 pounds per square inch 
of area on piston valve, take a flat valve 14 inches 
wide and 24 inches long would be 24 X 14 inches 
3.36 square inches X by 120 pounds of steam = 
403.20; the flat valve has 309.60 pounds more pres- 



36 MARINE AND STATIONARY ENGINEERS CATECHISM 

sure than a piston valve; the piston valve has less 
friction by 309.60 pounds. 

Q. Which is the best way to run a stationary 
engine, over or under? 

A. Over, because the pressure of the crosshead and 
the main shaft is downward on the foundation 
instead of up against the guide or caps. 

Q. The question is often asked what is the best 
way to set a piston valve? 

A. Place the engine on top or bottom centre, 
place the piston valve in its place, then give the 
piston valve the full opening of the exhaust and the 
piston valve is set nearly correct. 

Dynamo Electric Questions 

A dynamo is a machine by means of which 
mechanical energy is converted into electric energy. 
A dynamo electric generator or dynamo electric 
machine is ordinarily constructed as follows: Parts: 
armature, the field magnets, the commutator, and 
collecting brushes. A dynamo is classified under two 
headings: first, direct current generator; second, 
alternating current generator. The direct current 
generator is divided into series wound machine, 
shunt wound machine and compound wound machine ; 
and the alternating current are classified with respect 
to the character of the current they develop. In 
this case it may be said that there are single-phase 
machines and two-phase machines and three-phase 
machines. 



MARINE AND STATIONARY ENGINEERS CATECHISM 87 

Among alternating- current generators are found 
forms of construction of a space character in which 
neither the armature wire nor the field being pro- 
duced. The series wound dynamo is generally em- 
ployed for a system of electric lighting in which a 
constant current is necessary, such as high-tension 
arc lighting. For instance the function of this 
type of generator is to provide a current of 10 or 12 
amperes and a voltage that is capable of being 
adjusted by special means to suit the number of 
lamps in use. The arc lamps are connected in series. 
Each lamp takes the same amount of voltage. 
If tw^enty or thirty lamps are connected twenty or 
thirty times the volts required for one lamp is the 
total voltage to be generated and would equal 
20 X 50 or from 1000 to 1500 volts. Arc lamps 
as now used may be of the open or closed arc type; 
by this is meant that the carbon either burns in 
the open air, lasting only about eight or ten hours, 
or enclosed in small globe. Each lamp takes 50 volts 
if of the open air type; if of the closed globe type, 
each lamp will take about 80 volts. The dynamo 
must be able to automatically raise or lower its 
voltage when the lamps are turned on or off. 
When more lamps are added to the line, more 
voltage will be required. In fact, as much more as 
there are extra lamps. When lamps are cut off, 
less voltage will be required in proportion to the 
number of lamps. For instance, if ten of the closed 
globe type are added to the circuit of a series wound 
dynamo by simply turning them on, 10 X 80 or 800 



38 MARINE AND STATIONARY ENGINEERS CATECHISM 

volts more must be sent into the line; on the other 
hand, if 10 lamps are cut out 800 volts less in the 
line will do. 



Sparking on a Dynamo 

Sparking may be caused by too great a load on 
the dynamo or by wrong position of the brushes. 
One brush may not be opposite the other in a two 
pole machine, or the brushes may not be properly 
adjusted on the commutator if they belong to a 
multipolar machine On a four pole machine they 
should be 90 degrees apart; on a six pole machine, 
60 degrees apart. The simplest way of getting the 
correct distance between brushes is to count the 
commutator bars and divide them by the numbers 
of poles of the generator. Sometimes sparking at 
the commutator is caused by the bars being loose; 
or the mica and the bars may be projecting beyond 
the brushes. In general the difficulty is frequently 
found in the more rapid wearing away of the copper 
bars before the mica itself has worn down. The 
mica • is harder than might be expected, and the 
brushes do not affect it. Sandpapering the commu- 
tator is of little or no use; the only remedy is the 
turning down of the commutator. The best way to 
do this is by a lathe or by a special commutator 
turning device. 

Q. How do the alternating and the direct 
current generators differ? 



MARINE AND STATIONARY ENGINEERS CATECHISM 39 

A. The direct current generator uses a commutator 
in order to send out a current. Following always 
in the same direction alternating current generators 
use collecting rings, which permit all the alterna- 
tions generated within the armature to occur outside 
in connecting circuits. 

Q. What reverses the direction of a current in 
a conductor? 

A. The fact that it has being moved past a north 
pole or a south pole. The electro-motive force tends 
to send a current in one direction when the conduc- 
tor passes a north pole and in the reverse direction 
when it passes a south pole. 

Q. What is the action of the commutator and 
brushes? 

A. To permit all positive impulses to flow into 
one brush or set of brushes and all negative impulses 
to flow^ into the other brushes or other set of brushes. 

Q. What causes heating a commutator? 

A. Bad contact between the brushes and the com- 
mutator, a small commutator, too much pressure 
from the brushes, or a brush of too great a resistance. 

A brush should never be lifted off the com- 
mutator while the dynamo is running. Every 
binding screw should be examined, and if necessary 
tightened every day, as they are liable to be loosened 
by a slight jar of the dynamo. 

It is advisable to run a new dynamo a few 
hours or even a day without any load on in order 
to have everything in proper working order before 
putting on the load, which should be done gradually. 



40 marine and stationary engineers catechism 

Starting and Charging an Ammonia Compressor 

As each type of ammonia compressor has its own 
feature of construction, each particular machine 
will require special care and laid down to suit all 
cases. There are, however, some general principles 
which are attached to all types based on the com- 
pression system. Before charging an empty machine 
with ammonia all air must first be expelled, this 
is done in various ways, one method often used is 
to pump the system full of gaseous ammonia and 
shut the engine down, allowing the water to flow 
in the condensor until all the ammonia in the system 
is condensed, the liquid ammonia being heavier 
will drop to the bottom of the system, the valve 
can then be opened at the highest part of the system 
and the pressure of the ammonia gas will indicate 
when to shut off the valve, the system can then 
be allowed to stand six or twelve hours, and the 
valve again opened; if there is any air remaining 
in the system it will be driven out when the valve 
is again opened. Before charging the system 
it can be thoroughly tested by working the com- 
pressor and permitting air to enter at the suction 
through the special valve provided for that purpose, 
and it should be perfectly tight at 200 or 250 pounds 
per square inch, and should be able to hold that 
pressure without loss while testing the system 
under air pressure. It should be carefully and 
thoroughly cleaned of all dirt and moisture by 
blowing out. In some cases it is impossible to get 



MARINE AND STATIONARY ENGINEERS CATECHISM 41 

rid of all of the air from the phirit by means of the 
compressor, therefore, it is advisable to insert the 
requested charge of ammonia gradually; sometimes 
from 60 to 70 per cent, of the fuel charge is put in, 
and the air remaining in the system is allowed to 
escape through the purging cocks with as little 
loss of gas as possible; subsequently an additional 
quantity of ammonia, once or twice a day, is inserted 
until all the air has been displaced and the complete 
charge has been introduced. To charge the machine 
the drum of ammonia is connected through a suit- 
able pipe to the charging valve. The machine 
should be run at a slow speed when sucking the 
ammonia from the tank, with the discharge and 
suction valve wide open. When one of the tanks 
is emptied the charging valve is closed and another 
tank placed in position, and the process continued 
until the machine is charged for work, when the 
charging valve can be closed, and the main expan- 
sion valve opened and regulated. A glass gajuge 
upon the liquid receiver will show" w^hen the latter 
is partially filled and the pressure gauge, as well as 
the gradual cooling of the brine in the refrigerator 
and the expansion pipe, being covered with frost, 
will indicate when sufficient ammonia to start work- 
ing has been inserted. The machine having been 
started and the regulating valve opened the tempera- 
ture of the delivery pipe should be carefully noted, 
and if it shows a tendency to heat, then the regu- 
lating valve must be opened wider; while if it should 
become cold, the valve must be slightly closed, the 



42 MARINE AND STATIONARY ENGINEERS CATECHISM 

regulation or adjustment thereof being continued 
until the temperature of the pipe is the same as the 
cooling water which leaves the condenser if the 
charge of ammonia is insufficient, the delivery pipe 
will become heated. Even the regulating valve 
is wide open. Among the signs which denote the 
healthy working of the plant, beside the fact that it 
is satisfactorily performing its proper refrigerating 
duty, the vibration of the pointer of the pressure 
and vacuum gauge which clearly makes every 
stroke of the piston, the frost on the exterior of the 
ammonia pipes, the liquid ammonia can be dis- 
tinctly heard pouring through the regulation valve 
in a continuous stream, and the difference in tem- 
perature between the condenser and the cooling 
water and the refrigerator and the brine. 

Q. Does the temperature of steam at ordinary 
pressure contain heat enough to ignite wood? 

A. Not without the intervention of some other 
substance, such as linseed oil, greasy rags, or iron 
turnings. 

Q. How do you explain that? 

A. Because we know that the temperature of 
superheated steam is only about 400° Fahrenheit, 
and it requires more than double that temperature 
to ignite wood. 

Q. How is the power of steam engine expressed? 

A. In a horse-power. 

Q. What is a nominal horse-power? 

A. 33,000 pounds raised one foot high in one 
minute. 



MARINE AND STATIONARY ENGINEERS CATECHISM 48 

Q. Why is it that 33,000 pounds raised one foot 
high in one minute is adopted as a standard for a 
steam engine? 

A. Before the introduction of the steam engine 
it was found by experiment that with the average 
horse the best speed for work was at the rate of 
2| miles per hour, and at that rate of speed a 
horse could raise at perpendicular a weight of 
150 pounds 220 feet high in one minute, which is 
equivalent to 33,000 pounds raised one foot high in 
one minute, and was taken by Watt^ as a standard 
for a horse-power, and is universally received as 
such. For instance, an engine of 60 horse-power 
can raise 33,000 pounds one foot high in a second 
or an engine of 420 horse-power w^ould raise 33,000 
pounds one foot high in y of a second. 

Q. The question is often asked why is it necessary 
to make the longitudinal seams so much stronger 
than the transverse or girth seam. 

A. The reason is that the strain on the longitudinal 
seam is twice that of the transverse seam. In some 
types of boilers it is more than twice, for in the return 
tubular or a boiler having tubes and stays from head 
to head they relieve the transverse seam while the 
longitudinal seam has the full load to carry. On 
the transverse or girth seam the pressure would be 
the area of the head being required of the diameter 
2 X .7854 by the total pressure strain this pressure 
acts endwise along the boiler tending to pull it 
apart, and it is withstood by the plate of the boiler, 
and where this comes together at the girth seam 



44 MARINE AND STATIONARY ENGINEERS CATECHISM 



the length of each girth seam is the same as the cir- 
cumference of the boiler — that is, it is equal to 
.7854 X by diameter squared X by the pressure 
divided by 3.1416 X by diameter, since 3.1416 is 
exactly 4 times .7854, we find from the above cal- 
culation that the strain on the girth seam per inch 
of its length is 

diameter X by pressure 
4 

If a two inch pipe discharges 3600 gallons of water 
per minute, what is the velocity in feet per second? 

one minute 60)3600(60 

360 60)60(1 

60 

one foot per second — 



MARINE AND STATIONARY ENGINEERS CATECHISM 45 



Rule for a Pump 

A pump with a water end 5 inches in diameter 
and the steam end 6 inches in diameter with 70 
pounds pressure the pump is pumping against 
100.8 pounds. Suppose you wanted to change the 
water end of the pump to pump against 157.5 pounds 
per square inch, what would be the diameter of 
the pump end. 

Diameter of pump is 5 X 5 = 25 square inches 
X 100.8 pounds = 2520.0 -^ by the pressure the 
pump is to pump against which is 157.5 = 16 and 
the square root of 16 = 4 = diameter pump. 



iameter 5 
5 


100.8 
25 




25 


5040 
2016 






157.5)2520.0(16 
1575 


16(4 
16 




9450 
9450 



diameter of pump is 4 inches 



46 MARINE AND STATIONARY ENGINEERS CATECHISM 



Donkey Pump 

To find the number of gallons a pump will pump 
allowing 231 cubic inches to a gallon single acting 
pump number of strokes per minute 100 diameter 
of the pump 4 J. Length of stroke is 8 inches. 

4 . 5 diameter of pump 
4.5 

225 

180 

20.25 

.7854 



8100 
10125 
16200 
14175 

15.904350 

8 inch stroke 



127.234800 

100 revolutions 



231)12723.480000(55.08 number of gallons per minute 
1155 

1173 
1155 

1848 
1848 



MARINE AND STATIONARY ENGINEERS CATECHISM 47 



Donkey Pump 

Take a pump with the steam end 6 inches in 
diameter, 60 pounds of steam, the pump end is 
4 inches in diameter, what pressure per square 
inch will this pump pump against? 



6 steam end 
6 

36 

60 steam pressure 

square of the 16)2160(135 pounds this pump will pump 
pump end 16 against 

56 

Take the same pump to find the height the pump 
will pump w^ater in feet. Take a constant of 2.305 
X by the pressure the pump will pump against 
that will give the height the pump will pump water 
in feet. 

2.305 

135 the pump will pump against 

11525 
6915 
2305 



311.175 
This pump will pump 311 feet high. 



48 MARINE AND STATIONARY ENGINEERS CATECHISM 



The Horse-Power of a Pump 

What is the horse-power of a pump with the 
following dimension: Diameter of pump 10 inches, 
revolutions per minute 80, 156 pounds total head 
pressure per square inch on pump, stroke is 28 inches. 



.7854 

100 square of pump 



78.5400 

28 stroke 



6283200 
1570800 



2199.1200 

80 revolution per minute 

one cubic 

ft. 1728)175929.6000(101.8 cubic feet 



101.8 cubic feet 
62 . 5 pounds to cubic foot 

5090 
2036 
6108 



6362.50 

156 total pressure on pump 



3817500 
3181250 
636250 



33,000)992550.00(30. 
99 

25 
This pump is 30 horse-power and a little over. 



MARINE AND STATIONARY ENGINEERS CATECHISM 49 



Donkey Pump Rule 

If you were going to test your main boiler in 

your ship to put 120 pounds of cold water pressure 

on your main boilers, and if you had a donkey 

boiler, what pressure of steam would you carry 

on your donkey boiler to put 120 pounds of cold 

water pressure on your main boilers with a pump 

6 inches in diameter and the steam end 10 inches. 

6 water end 
6 

36 

120 cold water pressure 

720 
36 



square of pump 100)4320 . (43 . 2 it v:ould take 44 -pounds 
end 400 



320 
300 

200 
200 



Q. What is the horse power of a boiler? 

A. The evaporation of 30 pounds of water per 
hour from feed water 100° Fahrenheit into steam 
at 70 pounds' gauge pressure has been adopted as 
the horse-power of a boiler. 



50 MARINE AND STATIONARY ENGINEERS CATECHISM 

To find the thickness of a casting to stand a 
certain pressure when you have the inside dimen- 
sion and the steam pressure. We will say that 
the casting is 20 inches inside diameter, 95 pounds 
of steam. 

Example 



95X20 , „ „ 

95 steam pressure 
20 inside diameter 



constant— 4,000) 1900 . 000( . 475 

16000 . .475 



30000 



0.6 



28000 1.075 thickness = Ij^ 



20000 
20000 



To find the pressure on a guide slipper area of 
piston X by total pressure X by length of crank 
pin, divided by the area of the guide slipper X by 
length of the connecting rod. 



MARINE AND STATIONARY ENGINEERS CATECHISM 51 

To Find the Pressure on Crank Pin 

Area of the piston X by total pressure divided 
by the length of the crank pin X by diameter of 
crank pin. 

To Find the Pressure on Thruss Bearing 



First get the horse-power of your engine, we will 
say 175, revolutions 140, pitch of wheel is 5 feet; 
allowing 2240 pounds to a ton then multiply 
175 X 33,000 = 5775000 - 140 X by 5 - 700. 



140 175 horse-power 
5 33,000 

700 525000 
525 




700)5775000(825000 
5600 


2240)825000(3.69 tons on shaft 
6720 


1750 
1400 


15300 
13440 


3500 
3500 


18600 
17920 



three tons and over half ton 



OZ MARINE AND STATIONARY ENGINEERS CATECHISM 



Side Wheel Steamer 

To find the number of revolutions that a steam 
engine has to make per minute with a paddle wheel 
17 feet in diameter to make 17 J miles per hour; 
allowing 6080 feet in one mile. 



3.1416 

17 diameter 


6080 
17.5 miles 


219912 
31416 


30400 

42560 
6080 


53.4072 

60 one minute 


3204)106400.0(33 revolutions 
per minute 


3204.4320 



Take the same example to find the numher of 
miles it will make in 33 revolutions per minute. 



3.1416 

17 diameter wheel 



33 



219912 53.4)6080.0(113 60 one mmute 

31416 534 

113)1980.(17.5 

53.4072 740 113 

534 

• 850 

2060 791 

1602 

590 

17.5 miles per hour 565 



How many miles will a ship travel per hour when 
the engine is making 80 revolutions per minute, 



MARINE AND STATIONARY ENGINEERS CATECHISM 5e3 

pitch of wheel 20 feet, allowing 20 per cent, for slip, 
allowing 5280 feet in a land mile. 



80 X 60 X 20 




80 revolutions 
60 one hour 


5280 


• 


4800 

20 pitch of wheel 

5280)96000(18.18 
3.63 




18.18 

20 per cent, 


3.6360 



14 . 55 miles the ship makes 

If the pitch of a wheel is 16 feet, how many revo- 
lutions must it make to advance 10 knots per 
hour, a knot being 6080 feet? 



6080 X 10 
16 


6080 one knot 
10 knots 


38.00 revolutions 


16) 60800 (38 . 00 revolutions 
48 

128 
128 



54 MARINE AND STATIONARY ENGINEERS CATECHISM 

If a ship has a wheel 18 feet pitch, 75 revolutions 
per minute, allowing 6080 feet in one knot, how many 
miles will the engine make, and what is the slip of 
the wheel; observation is 295 miles in 24 hours in 
one day? 



18 ft. pitch 
75 revolutions 

90 
126 

1350 

60 one hour 



81000 

24 one day 



324000 
162000 



one knot 6080)19440000(319 knots by wheel 
18240 



319 knots by wheel 

12000 295 observations 

6080 

knots by 3 19) 24. 0000 (7. 52 slip of 

59200 wheel 2233 wheel 

54720 

1670 

1595 

750 
638 



iMARINE AND STATIONARY ENGINEERS CATECHISM 55 

Rule to find how far a steamer will run in six 
minutes, allowing 1760 yards in a mile, 175 revolu- 
tions, pitch of wheel 8 feet, not including the slip 
of the wheel, allowing 3 feet to a yard. 

175 revolutions 
8 pitch of wheel 

1400 

6 minutes 

one yard 3)8400 feet in 6 minutes (2800 
6 

— 1760)2800.00(1.59 

24 1760 



24 



10400 

8800 

16000 
15840 



This boat will run one mile and little over one-half mile in 
6 minutes. 



56 MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to find the pitch of a wheel when you know 
your ship is making 12 knots per hour; to get the 
pitch of the wheel without taking the ship out of 
the water, allowing 60 minutes one hour, 15 per cent, 
off for slip, 120 revolutions, allowing 6080 feet in a 
mile. 



one hour 60)6080.0(101.3 

60 101.3 

12 knots 

80 

60 2026 

1013 

200 

180 15 off for slip 85)1215.60(143.0 
. 85 

365 
340 

256 
255 



10 



Revolutions 120)143.00(11 .9 pitch of wheel 
120 

230 
120 

1100 
1080 

Pitch of wheel is 11 feet and little over. 



MARINE AND STATIONARY ENGINEERS CATECHISM 5/ 

To find how many miles this ship makes without 
any sKp of the wheel allowing 6080 feet in a mile, 
8 feet pitch of wheel, 90 revolutions per minute. 
How many miles will this ship make in five days? 



90 revolutions 
8 pitch of wheel 

720 

60 one hour 



43200 

24 one day 



172800 
86400 



1036800 

5 days 

6080)5184000.00(852.63 miles ship makes 
48640 in five days 



32000 
30400 

16000 
12160 



38400 
36480 

19200 
18240 



58 MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to find the slip of the wheel when you have 
an engine counter; the pitch of the wheel 20 feet. 
The register stands before starting 900, at the finish 
the register stands 14,000. What is the slip of the 
wheel? 

14,000 
900 



13100 

20 pitch of wheel 



262000- number of feet engine makes 
6080 one knot 



255920 = 100 per cent. 

Number of 

feet engine 262000)255920.00(97 per cent, slip 
makes 2358000 



2012000 
1834000 



Pressure on piston: What would be the pressure 
per square inch on a piston 18 inches in diameter 
with 100 pounds of steam? 



.7854 18 

324 18 



31416 144 

15708 18 

23562 

324 square inches 



area 254.4696 

100 lbs. steam pressure 



25446. 9600= pressure on piston 



MARINE AND STATIONARY ENGINEERS CATECHISM 59 



Engine Counter 

The counter is used on all steam vessels. To 
find the number of revolutions the engine makes 
in 10 days, 14 hours, 13 minutes, and 40 seconds. 
The engine started with 967 revolutions, and after 
the voyage the register stood 696049. 696049 - 967 
= 695082, when the engine stopped. Now then 



24 hours one day 
10 days 


696049 when stopped 
967 when started 


240 
14 hours 

254 

60 one hour 


695082 difference when 
stopped 
10)40 seconds 

4 


15240 minutes 
13 minutes 


10)60 seconds 

6 
6 nurnber of revolutions per minute 


15253.4)695082.00(45.5 
610136 


849460 
762670 


1 


867900 
762670 




1052300 
915204 





This engine makes 45.56 revolutions per minute. 



60 MARINE AND STATIONARY ENGINEERS CATECHISM 



Safety Valve 

To find the weight to be placed on a lever safet}" 
valve: Diameter of valve 4|; steam pressure is 100 
pounds; fulcrum is 3 inches; length of lever is 30 
inches; weight of lever is 25 pounds; weight of valve 
and stem is 9 pounds. 



25 weight of lever 


4.5 diameter 


15 half length 


4.5 


125 


225 


25 9 valve and stem 


180 


3 fulcrum 




375 — 


20.25 


27 27 


.7854 



402 8100 

10125 
16200 
14175 



15.904350 area of valve 
100 steam 



1590.435000 

3 fulcrum 



4771.305000 
402 

Length lever 30)4369.305000(145.64 weight of hall 
30 

136 
120 

169 
150 

193 
180 

130 
120 



MARINE AND STATIONARY ENGINEERS CATECHISM 61 



Safety Valve 

If a safety valve area is 7 inches, steam pressure 
is 60 pounds, fulcrum is 3 inches length, lever 24 
inches long, weight of valve and stem 6 pounds, 
weight of lever 9 pounds, what would be the weight 
of the ball to be placed on the end of the lever? 



12 half length of lever 7 area of valve 

9 weight of lever 60 steam pressure 

108 6 valve and stem ' 420 
18 3 fulcrum 3 fulcrum 

126 18 1260 

126 subtract 



Length lever 24)1134.00(47.25 weight of ball 
96 



174 
168 



Work the example back- 60 

ward to find the steam 48 

pressure. 

120 
7 area 47.25 ball 120 
3 falcrum 24 lever 



21 18900 

9450 



1134.00 
126 



21)1260.00(60 steam pressure 
126 



62 MARINE AND STATIONARY ENGINEERS CATECHISM 



Safety Valve 

We want to find what steam pressure it will take 
to make a safety valve blow off with a direct 
weight on top of a valve and stem without any 
lever; valve is 4 inches in diameter; weight of valve 
and stem is 12 pounds; the ball weighs 100 pounds. 



ball 100 pounds .7854 

12 valve and stem 16 square of valve 

112 dead weight 47124 

7854 



12 . 5664 area of valve 

12.5664)112.00000(8.91 or nearly 9 pounds of steam 
1005312 



1146880 
1130976 

159040 
125664 

112 dead weight 
100 steam 



8.91)11200.00(1257.00 
891 

12.5664)1257.0000(100 weight of ball 

2290 125664 

1782 



5080 
4455 



3600 



6250 
6237 

It takes 8 pounds 91 one-hundredths, nearly 9 pounds to 
raise the valve. Then work it backward to find weight. 



IVIARINE AND STATIONARY ENGINEERS CATECHISM 63 



Rule for a Round Tank 

If a tank is 6 feet in diameter what will be the 
height of the tank to hold 2000 gallons, allowing 
231 cubic inches to a gallon? 



72 diameter of tank in inches 

72 


144 

504 




5184 

.7854 




20736 
25920 
41472 

36288 




231)4071.5136(17.6256 
231 

1761 
1617 


17.6256 

12 constant 


352512 
176256 


1445 

1386 


211.5072 


591 

462 

1293 
1155 


211)2000.00 gallons(9. 47 
1899 height 

of tank 

1010 
844 


1386 
1386 


1660 
1477 



Height of this tank is 9.47 nearly 9|. 



64 MARINE AND STATIONARY ENGINEERS CATECHISM 



Round Tank 

To find how many gallons this tank will hold, 
allowing 231 cubic inches to a gallon. The tank 
is 28 inches in diameter and 4 feet high. x\lways 
take the tank in inches when you want to get the 

gallons. 

28 diameter 

28 

224 
56 

784 
.7854 



3136 
3920 
6272 

5488 

615.7536 area of tank 
48 height of tank 



49260288 
24630144 



231)29556. 1728(127.94 number of gallons this tank will 
231 hold 

645 
462 

1836 
1617 

2191 
2079 

1127 
924 



MARINE AND STATIONARY ENGINEERS CATECHISM 65 



Square Tank 

To find the number of gallons this square tank 

will hold, allowing 231 cubic inches to a gallon. 

Tank is 5 feet 3 inches long, 3 feet 4 inches wide, and 

4 feet deep. 

63 length of tank 
40 width of tank 

2520 
48 deep 



20160 
10080 

231)120960.00(523.63 number of gallons this tanJc 
1155 will hold 

546 
462 

840 
693 

1470 
1386 

840 
693 



66 INIARINE AND STATIONARY ENGINEERS CATECHISM 



Round Tank 

To find the number of tons of water this tanlv 
will hold, half full, allowing 32 cubic feet per ton. 
Diameter of tank is 16 feet, and it is 18 feet high. 



diameter 16 

of tank 16 .7854 
256 



96 

16 47124 

39270 

256 15708 



half tank 2)201.0624(100 
2 

• 100 

01 18 height of tank 

800 
100 



one ton 32)1800.00(56.25 tons 
160 of water 

200 
192 

80 
64 

160 
160 



This tank will hold fifty-six tons and a quarter. 



MARINE AND STATIONARY ENGINEERS CATECHISM 67 



Round Tank with Three Dimensions 

To find the number of gallons this tank will hold, 
allowing 7.48 cubic feet to a gallon, the number of 
gallons in cubic feet. This tank is 3 feet in diameter 
at the top, 9 feet high, and 5 feet at the bottom. 

5 - + 3-^ + 5 X 3 = 49 X .7854 = 38.4846 X 9 height of tank 
3 



3 ft 



.7854 
49 

70686 
31416 

38.4846 

9 height 



top 3)346.3614(115.45 
3 



13 
12 



16 
15 




5ft 



115.45 

7 . 48 number of gallons 

in cubic foot 

92360 
46180 
80815 

863.5660 
863 gallons in this tank. 



68 MARINE AND STATIONARY ENGINEERS CATECHISM 



Round Tank to Find the Diameter 

This tank is 4.02 feet high, containing 400 gallons, 
allowing 6.25 gallons to a cubic foot. 

400 gallons , . ,. 

= 15.9 -^ .7854 = V20.24 = 4.49 ft. in diameter 



4.02 X 6.25 



4.02 height 

6 . 25 gallons to cubic foot 

2010 
804 
2412 

gallons 



25. 1250)400.00000(15.900000 
251250 

.7854) 15.900000(20.24 

1487500 15708 
1256250 



19200 



2312500 15708 
2251250 



20.2400(4.49 square root 
16 

84)424 

336 



8001 
This tank is 4.49 in diameter nearly 4| feet. 



MARINE AND STATIONARY ENGINEERS CATECHISM 69 



Flat Bottom Boiler 

To find the number of |-inch stays to put in flat- 
bottom boiler 18 feet 6 inches long, 12 feet 6 inches 
wide. The water is 12 feet 10 inches high with 
45 pounds of steam, allowing 6000 stress on stay. 
Constant 2.305 in a column of water 1 foot high 
and 1 inch in diameter. 



222 length of boiler (inches) 
150 width of boiler 



12)10000(8333 
96 


11100 
222 


40 
36 


33300 
50.5 total pressure 


40 
36 


166500 
166500 


40 


3607)1681650.0(466 number of stays 
14428 

■ ■ ■ 875 




23885 .875 dec. of | 
21642 




22430 6125 
21642 7000 


2.305)12.8333(5.5 
11525 


.765625 

.7854 


13083 
11525 


3062500 
3838125 
6125000 
5359375 


45 steam 
5.5 water 

50.5 
Total pressure 


.6013318750 

6000 stress on 


3607.9912500000 



70 MARINE AND STATIONARY ENGINEERS CATECHISM 

Flat-bottom boiler, to find steam pressure: Boiler 
is 14 feet 6 inches long, 10 feet 7 inches wide; 65 
stays one inch and a quarter in diameter. The 
water in boiler 8 feet high, allowing 6000 stress on 
stay; constant 2.305. 

174 length of boiler 
127 width of boiler 

1218 
348 
174 



number 65)22098.0(339.9 square inches held up by one 
stays 195 stay 

259 
195 

648 
585 



height of water 

2.305)8.0000(3.4 

6915 


630 

585 

ssure 
339 


1.25 

1 . 25 diameter of stay 

625 
250 
125 


10850 
9220 


1.5625 

.7854 


21 steam 
3.4 

24.4 total pre 


62500 
78125 
125000 
109375 


1.22718750 

6000 stress on stay 




.9)7363.12500000(21 steam pressure 
6798 



5651 
3399 



MARINE AND STATIONARY ENGINEERS CATECHISM 



To find the working pressure on a round boiler: 
Single-riveted boiler, allowing 20 per cent, for 
double-riveted and holes drilled; diameter of 
boiler, 5 feet 6 inches; thickness of plate, f ; tensile 
strength, 60,000; factor of safety, J. 



6)60000(10000 


10000 




6 


.375 thickness 




50000 




diameter of boiler 


70000 




2)66(33 inches 


30000 




6 






33)3750.000(113.63 


6 


33 




6 




113.63 


- 


45 
33 


22.72 




136.35 




120 






99 




113.63 




steam 


.20 


210 


pressure 




198 


136 pounds 




2272.60 


120 
99 





Calculate the safe-working pressure on a corru- 
gated furnace, allowing 14,000 as a constant; thick- 
ness of furnace, i; diameter of furnace, 40 inches. 



40)14000(350 
120 

200 
200 



350 
. 5 thickness 



175.0 

steam pressure 



72 MARINE AND STATIONARY ENGINEERS CATECHISM 

To find the number of f-inch rivets to hold down 
a steam dome, smgle-riveted, with 120 pomids of 
steam; diameter of the dome, 32 inches; f rivet, 
xf hole; allow 6000 stress on rivet. 




.5184 area of tI hole 
6000 



3110.4000 



32 diameter 
32 " 

64 
96 



1024 

.7854 



3110)96509.9520(31 
9330 



3209 
3110 



4096 
5120 
8192 
7168 

804.2496 

120 steam 



160849920 
8042496 

96509.9520 



It will take 31 rivets, nearly 32 



MARINE AND STATIONARY ENGINEERS CATECHISM 73 

To find the diameter of a safety valve to place 
on a boiler with 75 square feet of grate surface, 
allowing 3 square feet of grate surface to one inch 
of area of valve : 

. 7854)25 .000000(31.83 square root Square feet 3)75(25 
23562 6 



14380 15 

7854 15 



65260 

62832 3 1 . 8300 (5 . 64 diameter of valve 

25 

24280 

23562 106)683 

636 



1124)4700 
4496 



Diameter of valve 5 . 64 
" 5.64 

2256 
3384 
2820 

31.8096 

.7854 

1272384 
1590480 
2544768 
2226672 



24.98325984 

3 square feet of grate 



74.94977952 
74 . 94 square feet of grate surface nearly 75 feet. 



74 MARINE AND STATIONARY ENGINEERS CATECHISM 

What would be the pitch of a stay bolt if the plate 
was J inch thick, the steam pressure 40 pounds, 
and thickness of the plate under yg use constant 112, 
any thickness of plate over i^ up to f , use constant 
120 squared in 16 of inches? 



120 constant 




64 in 16 squared 


480 




720 




steam pressure 40)7680(192 




40 






1|92 


368 


1 


360 


— 




24)92 


80 


96 


80 


— 



square root of 192 
1|92(14 pitch of stay 
nearly 14 inches 



Rule to find the thickness of plate in a boiler 
when you have TS and steam pressure and dia- 
meter: Diameter of boiler 36 inches, steam pressure 
is 104 pounds, TS 45,000, factor of safety f. 





104 steam 




18 half diameter boiler 


6)45000(7500 




42 


832 




104 


30 

30 




7500)1872.0(.25 thickness of the 


— . 


boiler 



MARINE AND STATIONARY ENGINEERS CATECHISM /;> 

The stays of a boiler are IJ diameter; the steam 

pressure is 39.27 pounds per square inch; allowing 

5000 stress on stay; find the pitch of the stay. 

1.5 diameter of stay 
1.5 diameter of stay 



.7854 
2.25 


75 
15 


39270 
15708 
15708 


2 . 25 square of stay 


1.767150 

5000 stress on stay 


steam 3927)8835.750000(2.25 square root 
7854 
2.25(1.5 inches pitch of stay 

9817 1 

7854 

OCMOC 


19635 
19635 


125 



Take the same example as above: If the pitch of 

stay is 1.5 inches^ the steam pressure is 39.27 pounds 

per square inch. Allowing 5000 stress on stay, what 

would be the diameter of the stay? 

39 . 27 pounds pressure 
2.25 square of stay 



19635 

7854 
7854 



steam 39.27)88.3575(2.25 
7854 
2.25(1.5 diameter stay 

9817 1 

7854 ' 

25)125 

19635 125 

19635 



76 MARINE AND STATIONARY ENGINEERS CATECHISM 




A triple-riveted Scotch boiler, 4 rows of rivets 
in one shear; jf hole; pitch of double rows of rivets 
3f ; single pitch TJ; the diameter of the boiler is 72 
inches; thickness of plate, f ; tensile strength 55,000, 
allowing 40,000 for iron rivet; factor of safety 3-; 
but straps the same thickness as the shell of boiler. 

. 6903 area of H hole 
40000 iron rivet 



27612.0000 
This is what the rivet will stand 

40000 shearing of the rivet 
,85 per cent. 



200000 
320000 



34000.00 

40000 shearing of the rivet 



74000 . 00 shearing of all rivets 

Shearing of all of the rivets by taking 85 per cent, 
of the single rivet and adding the single to it gives 
the shearing of all rivets 74,000. 



MARINE AND STATIONARY ENGINEERS CATECHISM 77 



Triple-Riveted 



7 . 25 long pitch 
. 5 thickness 


7 . 250 long pitch 
. 9375 decimal of i| hole 


3625 

55000 TS 


6.3125 

. 5 thickness 


18125000 
18125 


315625 

55000 TS 


199.375000 
constant 


1578125000 
1578125 



199)1735.9375000(87 per cent, plate section 
2)72(36 .87 per cent. 



36 
5 

180 



.5 

435 
' 55000 TS 



2175000 
2175 



;6903 area it hole 
, 4 rows of rivets 



180)23925.000(132.8 
180 

592 
540 



.27612 

74000 shearing of all rivets 



110448000 
193284 



20432.88000 

2761 . 20000 single rivet added 

525 

360 constant 199)23194.08000(116 rivet shearing 

199 

1650 

1440 329 

199 

constant 

1304 
1194 



132 . 8 pounds of steam on this boiler. 



78 MARINE AND STATIONARY ENGINEERS CATECHISM 

To find the diameter of any stay with any given 
pressure: We will take 7500 pounds pressure per 
square inch. Allowing 6000 stress on stay, find 
diameter. Always use .7854 X 6000, gives what a 
one inch stay will hold, and divide that into the 
pressure and extract the square root of the answer 
= diameter of stay. 



.7854 
6000 


pressure 
4712)7500.00(1.59 
4712 




4712.4000 


27880 
23560 


1.5900(1.26 
1 

diameter stay 

22)59 1| 
44 




43200 
42408 






246)1500 
1476 



If the stay in a boiler is pitched 6X6 from centre 

to centre with 120 pounds pressure per square inch, 

what pressure is on the stay or what pressure is the 

stay holding up? 

6 pitch 



36 

120 steam 



720 
36 

This stay is holding 43 . 20 pounds 



MARINE AND STATIONARY ENGINEERS CATECHISM 79 

To find the working pressure of steam you would 
allow on a 1| round stay, allowing 6000 stress on 
stay; pitch of stay 6X6 from centre to centre. 

1 . 5 diameter stay . 7854 

1.5 2 . 25 square of stay 



75 39270 

15 15708 



2.25 



6 



15708 

1.767150 

6000 stress on stay 



6 36) 10602 . 900000(294 steam pressure on stay 
— 72 
36 

340 

324 

162 
144 



To find the working pressure per square inch 
you would allow 1 J square stay, allowing 6000 stress 
on stay; pitch of stay 6X6 from centre to centre. 

1.5 
1.5 

75 
15 

2.25 
6000 

square of pitch 36)13500.00(375 pounds steam pressure. 



80 MAKINE AND STATIONARY ENGINEERS CATECHISM 

To find the diameter of any stay to hold up any 
pressure when you have the steam pressure and the 
pitch of the stay. Now we will take, for example: 
The pitch of stay is 8 X 8 inches pitch from centre to 
centre and steam pressure per square is 160 pounds. 
What is the diameter of the stay? Always use 
.7854 X 6000 stress on stay. 

.7854 8 pitch 

6000 8 



4712.4000 64 square of the pitch 

160 steam pressure 

3840 
64 

4712)10240(2.17 pressure per square inch 



square root 

2.17(1.47 diameter of stay 
1 

24)117 
96 



287)2100 
1909 



It will take 1| stay to hold this pressure. 



MARINE AND STATIONARY ENGINEERS CATECHISM 81 



Rule to find : If there were a number of stays in a 
flat surface, and if one was to give way, what extra 
pressure would it throw on the other stays in the 
boiler? The stays are 12 X 12 centre to centre; the 
stay is If inches in diameter; steam pressure is 70 
pounds. What extra strain will be put on the other 
stays, allowing J the pressure after the stay gave 



awayr 

12 

12 pitch 

24 
12 

144 
70 steam 



1.625 

1 . 625 diameter of stay 



10080 strain before broke 



8125 
3250 
9750 
1625 

2.640625 

.7854 

10562600 
13203125 
21125000 

18484375 



area of stay 2.0739468850 

2.073)10080.0000(4862.4 after stay broke 
3)4862.4(1620.8 8292 

3 



18 
18 

6 
6 

24 
24 



17880 
16584 


1620.8 
after broke 4862.4 


12960 
12438 


6483.2 

strain thrown 

on stays 


5220 
4146 


10740 
8292 





82 MARINE AND STATIONARY ENGINEERS CATECHISM 

To find the number of square inches over the top 
of the tubes in the boiler: height, 12 inches; cord, 
48 inches; take f cord. 




48 
2 the cord 

3)96(32 
9 



32 

12 height 

64 
32 

I of cord 384 

18 one-third cord 



402 square inches in this 402 
space over tubes 

12 height 
12 

24 
12 

144 

12 height 

288 
144 

twice the cord 96)1728(18 one third of cord 
96 

768 

768 



402 square inches in this space over the tubes. 



MARINE AND STATIONARY ENGINEERS CATECHISM 83 

To find the working pressure of a straight furnace 
44 inches in diameter, 48 inches long, thickness of 
plate i inch, using a constant 51.5 — 10.3 — 18.75 



YT) times the pressui'e 

on con vexed heads is 18.75 constant 

pressure on concaved .8 = j o 

head 

150.00 
49.44 



constant 
diameter 44)51.50(1.17 
44 



100.56 
1.17 

70392 
10056 
10056 



steam pressure 117.6552 



75 

44 

310 
308 



1.03 constant 
48 

824 
412 



49.44 



Required the working pressure on convex heads, 
concave heads, radius 52 inches, TS 60,000, thickness 
of plate J, factor of safety ^. 



5)60,000(12,000 
5 



10 
10 



12,000 

.5 thickness 



half radius 26)6000.0(230 
52 

80 

78 



230 

.8 



184.0 



20 



230 pounds on convexed head. 
184 pounds on concave head. 



84 MARINE AND STATIONARY ENGINEERS CATECHISM 

The correct rule to find the workmg pressure on 
any boiler and percentage of the plate compared 
to the solid part of the boiler and the rivet shear: 

Pitch of rivet 2|, hole or rivet xf^ thickness of 
plate I, two rows of rivets, TS 50,000, diameter 
of boiler 60 inches, factor of safety ^, allowing 45,000 
for steel rivet. 

2 . 75 pitch of rivet 2 . 7500 pitch 

.375 thickness of plate .8125 decimal xf 

1375 2.75)1 .9375(70 percentage of plate 

1925 1925 

825 

125 

103.125 

constant area of if hole .51849 

. 2 rows of rivets 



constant 103)10369.8(100 
30 
6 . 70 per cent. 100 

.375 45000 steel rivet 

180 



350 500000 

490 400 

210 

TS 50000)4500 . 000(90 rivet 

. 26250 450 shear) 

50000 TS 



180)13125.00000(72 steam pressure 
1260 

525 
360 



MARINE AND STATIONARY ENGINEERS CATECHISM 85 

To find the tensile strength of a boiler, single- 
riveted, with holes drilled; steam pressure 125 
pounds, diameter of boiler 40 inches, thickness of 
plate J inch, factor of safety J. 

125 steam 
6 factor safety 

750 

20 haK diameter boiler 



thickness .25)15000.00(60000 TS of plate 
150 



To find the diameter of the same boiler as above: 
TS 60.000, thickness of plate J, steam pressure 125 
pounds, factor of safety |. 



steam 125 

6 safety 


60000 TS 
.25 thickness 


750 


300000 
120000 




750)15000.00(20 
1500 
20 

2 always twice 



40 diameter of boiler 
Diameter of boiler is 40 inches. 



86 MARINE AND STATIONARY ENGINEERS CATECHISM 

The rule for bracing the head of a boiler above 
the tubes: 

For example, will say that we have to brace in this 
boiler 353.77 square inches, the load to be carried 
by the braces will be equal to the area multiplied by 
the working pressure, which is 130 pounds per square 
inch: total load, 353.77 X 130 = 45,990 pounds. No 
boiler brace should be allowed greater stress than 
6000 pounds per square inch. The number of braces 
required may be found by dividing the total load by 
what one brace will stand, which in this case is 
45,990-^6000 = 7.66, say 8 braces having an area of 
one inch square, which corresponds to about 1| 
inches in diameter. The surface or area supported 
by each brace is found by dividing the area to be 
supported by the number of braces, which gives 
353.77 ^ 8 = 44.22 square inches; the square root 
of this number will give the distance between the 
braces or the pitch which is 6.64 inches or 6{^. 



MARINE AND STATIONARY ENGINEERS CATECHISM 87 




Example for bracing the head of the boiler: 

353 . 77 square inches 
130 steam 



1061310 
35377 



one brace 6,000)45990.10(7.66 number of stays— will say 8 
42000 



39901 stays 8)353 . 77(44 . 22 



36000 

39010 
36000 

square 

root 44.2200(6.64 

36 inches held 

up by one 

126)822 stav 

756 



32 

33 
32 



inches held up by 
one stay 



17 
16 



17 
16 



1324)6600 
5296 



6 . 64 square inches held up by one stay. In other words, 
6.64 is pitch of stay. 



88 MARINE AND STATIONARY ENGINEERS CATECHISM 

The quickest way to get the horse-power of a 
boiler is to get the number of square feet of the 
grate surface. We will say that we have got 50 
square inches of grate surface, multiplied by 50, 
multiplied by constant of 45, allowing 14 square 
feet to a horse-power. Example: 



50 
50 

2500 

45 constant 




12500 
10000 




one square ft. 144)112500.0(781.2 
1008 

1170 
1152 


14)781.2(55.8 horse 
70 power of 
boiler 

81 

70 

112 
112 


180 
144 

360 

288 



This boiler has 55 . 8 horse-power. 



MARINE AND STATIONARY ENGINEERS CATECHISM 89 

Rule to find the correct pitch of rivets in a single- 
riveted seam of a boiler : If the thickness of the plate 
is f , and the tensile strength is 60,000, the rivet 
J, the hole is yf , the shearing strength of the rivet 
is 40,000, then proceed. The area of jf hole is 
.6903 X 40,000, gives you the strength of the rivet, 
which is 27612.0000 ^ by f X 60,000 = 22500 and 
27612.0000 ^ 22500 = 1.2272; nearly li add the 
diameter of the hole: IJ + tI = 2j^ pitch. 

.6903 area of if hole 
40000 rivet 



27612.0000 strength of rivet 

22500)27612.0000(1.2272 nearly li pitch 
22500 



1.25 

dec. of if .9375 51120 
45000 



2.1875 = 2^ 



pitch 61200 

45000 



162000 
157500 



45000 
45000 



90 MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to find the correct pitch of double-staggered 
riveted lap-joint where the plates are made of 
steel f of an inch thick ; tensile strength of the plate 
is 55,000, the diameter of rivet is J, the diameter of 
hole is X6 J allowing 40,000 pounds shearing strength 
for rivet; two rows of rivets. 

.375 thickness | 
55,000 TS .6903 = area of M hole 

2 rows of rivets 

1875000 

1875 13806 

40,000 shearing of rivet 



20625.000 



20625 . 000)55224 . 0000(2 . 6775 
41250 

2.6775 

139740 .9375dec. of H 
123750 



3.6150 = 3i^ 

159900 pitch of rivet 
] 44375 



155250 
144375 

108750 
103125 



Pitch of this rivet is Sye. 



MARINE AND STATIONARY ENGINEERS CATECHISM 91 

Rule to find the coal burned per hour by indicated 
horse-power : Diameter of cylinder 42 inches, 48-inch 
stroke, 65 revolutions per minute, the diagram 
showing 55.6 pounds mean effective pressure on 
piston, consuming 30 tons of coal per day. Cal- 
culate the indicated horse-power developed and the 
consumption of coal per hour indicated horse-power. 



stroke 48 

2 twice 



96 

65 revolutions 



480 
576 

12)6240(520 
60 

24 
24 



.7854 
1764 cylinder squared 



31416 
47124 

54978 

7854 

1385.4456 

55 . 6 mean effective pressure 



83126736 

69272280 
69272280 



77030.77536 

520 feet per minute 



154061550720 
38515387680 



33)40056.00318720(1213 . 8 horse-power 
33 



2240 
30 
one 

day 24)67200(2800 

48 

192 
192 



70 
66 

45 
33 

126 
99 

270 
264 



1213.8)2800.000(2.31 pounds 
24276 per hour 

per horse- 
power 



37240 
36404 



18460 
12138 



92 MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to find the working pressure of steam you 
would allow on a straight furnace per square inch: 
diameter 44 inches, length 48 inches, thickness of 
furnace i, using three constants. 

Constants: . diameter 44)51 . 5(1 . 17 

51.5 44 

18.75 

1.03 18.75 75 

.8 = * 44 



150.00 310 

49.44 308 



100.56 
1.17 



1.03 



70392 48 length 

10056 

10056 824 
412 



117.6552 
Steam pressure is 117 pounds. 



49.44 



MARINE AND STATIONARY ENGINEERS CATECHISM 93 

The correct way to find the Uft of a valve. We 
will take a three-inch valve: 



3 in, valve 
3 in. valve 


.7854 

9 square of valve 


9 


9.4248)7.068600(.75 = f lift of valve 
659736 


471240 
constant 3.1416 471240 






9.4248 of 


valve 



There is another way to get the lift of the valve 
by dividing by J the diameter of the valve. Take 
the same valve as above, 3 inches in diameter : 

4)3.00(.75 = f 

28 

20 
20 

If you had one ton of coal and 300 pounds of 
ashes, what percentage of ashes would you have? 

Example : 

300 ashes 
100 per cent. 

one ton 2240)30000.00(13.39 percentage of ashes 
2240 



7600 
6720 



8800 
6622 

21800 
20160 



94 MARINE AND STATIONARY ENGINEERS CATECHISM 



Coal Bunker 

To find how many tons of coal this bunker will hold, 
allowing 40 cubic feet per ton. We will take this 
bunker in inches when you cannot get it in feet. 
Where you have three dimensions in feet, multiply 
the three dimensions in feet and you have cubic 
feet; where you cannot get it in feet, take it in 
inches and proceed this way: 



Length 18 ft 6 in. 


222 length in inches 


Depth 10 ft. 4 in. 


124 depth in inches 


Width 6 ft. 3 in. 






888 




444 




222 




27528 




75 width in inches 



137640 
192696 

one cubic foot 1728)2064600(1194.00 
1728 

40)1194.00(29.85 

3366 80 tons 

1728 — 

. 394 

16380 360 

15552 

340 

8280 320 

6912 

200 

200 



This bunker will hold 29.85 tons. 



MARINE AND STATIONARY ENGINEERS CATECHISM 95 



Coal Bunker 

To find the third dimension of a coal bunker to 
hold 40 tons of coal, allowing 42 cubic feet per ton. 
depth of bunker is 15 feet 6 inches, width of bunker 
is 12 feet G inches: 

186 depth 
150 width 

9300 
186 



one square foot 144)27900.00(193.75 
144 

1350 
1296 



540 
432 

1080 42 cubic feet 

1008 40 tons 



720 193.75)1680.0000(8.67 
720 155000 length 

— - of 

130000 bunker 
116250 



137500 
135625 



Length of this bunker is 8.67. 

Take page 96; you will find the bunker is figured 
in feet instead of inches. 



96 MARINE AND STATIONARY ENGINEERS CATECHISM 



Coal Bunker 

Take the same bunker as page 95. This bunker 
is done in feet to show you how to figure it in inches 
when you cannot get it in feet: Depth of bunker 15 
feet 6 inches, width 12 feet 6 inches, to hold 40 tons 
of coal, allowing 42 cubic feet per ton: 



15.5 depth 
12.5 width 

775 
310 
155 


. 


193.75 


42 cubic feet 
40 tons 




193 . 75) 1680 . 0000(8 . 67 length 
155000 




130000 
116250 




137500 
135625 



Length of this bunker is 8.67. 



MARINE AND STATIONARY ENGINEERS CATECHISM 9- 



Coal Bunker 

To find the average width of a coal bunker: 
Length of bunker, 45 feet; deptli of bunker, 16 feet; 
top of bunker, 25 feet; middle of bunker, 18 feet; 
bottom of bunker, 10 feet. Always divide by 6.. 



25 top of bunker 
72 four times middle 
10 bottom 



6)107.00(17.83 average width nearly IS feet 



47 
42 



50 

48 

20 

18 



Coal Bunker 

To find the average width: Top 10 feet, bottom 5 
feet. Always divide by 2 to get average width. 



10 top 
5 bottom 

Average width 7§ 2) 15.0(7 . 5 

14 



10 



98 MAKINE AND STATIONARY ENGINEERS CATECHISM 

Rule to balance weight on end of a lever; this 
lever has a weight of 154 pounds on the long end; 
the long arm is 34 J inches; the short arm is 15 J 
inches; what weight will it take on the short arm 
to balance the weight (154 pounds) on the long arm? 



154 



4^ 



34 1-2 IN. 



n 15 



154 weight on long arm 
34.5 length of long arm 

770 
616 
462 



short arm 15.5)5313.0(342 weight of ball on short arm 
465 



663 
620 



430 
310 



It will take a weight 342 pounds to balance the lever. 



MARINE AND STATIONARY ENGINEERS CATECHISM 99 

To find the stroke of an air pump when you have 
the dimensions of the air pump beam and the 
stroke of the engine. We will say the stroke of 
the engine is 3 feet, the length of the air pump 
beam is 5 feet over all, the long arm is 3 feet, and 
the short arm is 2 feet. 



< 3 FT 



O ^__ 2 

5 FT. 



This example is done in two ways; one way in feet and the 
other in inches. 

3 stroke of engine 
2 short arm 

Long arm 3)6(2 stroke of air pump 2 feet 
6 



36 stroke of engine 
24 short arm 

144 

72 

Long arm 36)864(24 stroke of air pump 24 inches 

72 

144 
144 



100 MARINE AND STATIONARY ENGINEERS CATECHISM 



To Point Off an Indicator Card 

STEAM LINE 




CURVE 



EXHAUST LINE 



The correct way to get the mean effective pressure 
on the piston is to lay your card out in 10 equal 
parts; each one of the lines denotes pounds of 
steam; take your scale, measure the length of each 
line, put it down on paper, then count it up; then 
multiply by the spring you use and divide by the 
10 spaces on your card; that will give you the mean 
effective pressure. 



Rule to Find the Pressure on a Piston. 



If the pressure of steam on the piston is 70 pounds 
when the engine is working full speed at 62 revolu- 
tions, and the speed becomes reduced to 50 revolu- 
tions, what would the steam pressure be? 



MARINE AND STATIONARY ENGINEERS CATECHISM 101 



revolutions 62 
62 

124 
372 

3844 



70 steam pressure 
50 revolutions reduced 

3500 

50 reduced revolutions 



3844)175000.00(45.52 reduced steam press- 
15376 ure 



21240 
19220 

20200 
19220 

9800 
7688 



To find the total pressure on a shaft either in 
pounds or tons: Mean effective pressure is 100 
pounds, the area of the piston is 350, stroke of the 
engine 24 inches, pitch of wheel 8 feet, revolutions 
of engine are 90 per minute. 



90 revolutions 
4 stroke 

360 feet per minute 

90 revolutions 
8 pitch of wheel 

720 



. 350 area of piston 

100 mean effective pressure 

35000 

360 feet per minute 



2100000 
105000 



720)12600.000(17500 pounds 
720 



5400 2240)17500.00(7.81 tons 
5040 15680 



3600 
3600 



18200 
17920 



2800 
2240 



102 MARINE AND STATIONARY ENGINEERS CATECHISM 

To find the thickness of a corrugated furnace, and 
find the diameter of the furnace: Steam pressure is 
175, diameter of furnace 40 inches, thickness of 
the furnace is J, constant 14,000. 



14000 constant 
. 5 thickness 

175 steam 

40 diameter steam 175)7000.0(40 diameter 
700 



14000)7000 . 0) . 5 thickness 
70000 



To find the weight of a safety-valve weight that 
is round: Get the diameter of the ball, then square 
it, then cube it, multiply it by a constant of 9, then 
divide it by a constant 64. 



7 diameter ball 
7 diameter ball 

49 
7 cube it 

343 

9 constant 



constant 64)3087.0(48.2 weight of ball 
256 

527 
512 

150 
128 



MARINE AND STATIONARY ENGINEERS CATECHISM 10)^ 

p To find the area of any diameter without using 
.7854. We will take 5 inches in diameter; first square 
it, then multiply it by .77, then multiply your 
answer by 2 twice; keep one figure to the right 

twice. 

.7854 5 diameter 

.25 5 diameter 

39270 25 

15708 .77 



19.6350 area 175 

175 
350 
350 



19.6350 area 

Example: To find the diameter of a shaft and to 
find the diameter of the steam pipe of a compound 
engine: High-pressure cylinder is 13 inches in diam- 
eter, low pressure cylinder is 27 inches in diameter, 
one-fifth of the low pressure cylinder is the diam- 
eter of the shaft; and one-quarter the diameter of 
the shaft subtracted from the diameter of the shaft 
is the diameter of the steam pipe. 



l.p. e. 




5)27.0(5.40 diameter of shaft 


25 




— 


4)5.40(13.5 one-quarter of shaft 


20 


4 


20 


— 


— 


14 




12 




20 5 . 40 diameter of shaft 




20 1 . 35 one-quarter of shaft 



4 . 05 diameter of steam pipe 

The diameter of the steam pipe is 4.05, and the diameter of 
the shaft is 5.4. 



104 MARINE AND STATIONARY ENGINEERS CATECHISM 

Example: To find the diameter of a steam pipe 
when you have the horse-power of the engine, using 
a constant of 6; we will say the horse-powder is 150. 

6)150(25 
12 

25(5 diameter of steam pip e 5 inches 

30 25 
30 — 

Example: To find how many times the steam 
expands .in compound engine and triple-expansion 
engine: Steam pressure 69 pounds, atmospheric 
pressure 15 pounds, 12 pounds pressure on the 
low-pressure cylinder. 

69 steam pressure 

15 atmospheric pressure 

pressure on low 12)84(7 steam expands 7 times 
84 



MARINE AND STATIONARY ENGINEERS CATECHISM 105 

Example: A blow-ofi' cock on the bottom is 14 
feet below the sea level and 9 feet below the water 
level in the boiler. What pressure per square inch 
would be required to blow the water out of the 
boiler? 



14-9 


14 


2.305 


9 




2.305)5.00000(2.16 
4.610 




3900 

2305 2 pounds — nearly 3 pounds. 




15950 
13830 



Example: To find the number of gallons of oil 
a barrel will hold, allowing 231 cubic inches in 
United States gallon: Take the largest part of the 
middle of the barrel and get the area of it, then 
multiply by the length in inches, then divide by 
231 = number of gallons; diameter of barrel 18 
inches, length 36 inches. 



18 X 18 X .7854 X 36 „ 
231 = -^^^^"' 



106 MARINE AND STATIONARY ENGINEERS CATECHISM 



The Question is Sometimes Asked: What 
IS Steel? 

Steel is iron with a mixture of carbon or an alloy 
of iron, the alloy being principally carbon steel. 
Steel can be melted like cast iron and welded like 
wrought iron. There are hard and soft steels, 
according to the process of production and proportibn 
of alloy. 



The Question is Sometimes Asked: What is 
Alloy? 

Alloy is a mixture or compound of two or more 
metals. Two parts of tin and six parts of lead is 
an alloy suitable for fusible plugs, and which melts 
at 380° Fahrenheit. An alloy is used to reduce 
the quality of one of the parts. 



MARINE AND STATIONARY ENGINEERS CATECHISM 10< 



Rule to Find Size of a Cylinder 

Rule to find the size tliat a cylinder should be 
in diameter: In the example we have 151 tons on 
piston and 64 pounds of steam on piston; then mul- 
tiply 15i by 2240 pounds in one ton, then divide by 
the steam pressure, then divide by .7854, then get 
the square root of the answer, and that will give you 
the diameter of cylinder. 

15 . 25 tons on piston 
2240 one ton 



61000 
3050 
3050 

Steam, pressure 64)34160.00(533.75 

320 

Constant .7854)533.7500(679 

216 47124 

192 

62510 

240 54978 

192 



75320 

480 70686 
448 

320 
320 



6|79(26 diameter of cylinder 
4 



46)279 
276 

Diameter of cylinder is 26 inches. 



108 MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to get the area of any diameter : First square 
the diameter, then multiply by .7854 = the area. 
Now to find the diameter : Divide the area by .7854, 
then get the square root of the answer = diameter. 
We will take a 10-inch valve. 

10 diameter 
10 .7854 

100 

100 

78.5400 area of 10 
.7854)78.5400(100 
7854 

1 1 00 (10 diameter of 
1 valve 

2)000 

Rule to find the horse-power of your dynamo: 
Multiply your volt meter by your amperes, and 
divide by 746 watts, will give you the horse-power 
of your dynamo; 746 watts equal one horse-power. 



MARINE AND STATIONARY ENGINEERS CATECHISM 109 



Rule to Find the Speed of a Wheel. 

Rule to find the speed which a wheel on a station- 
ary engine has to make to comply with the law; the 
limit speed is 6000 revolutions in feet per minute. 
We will take a wheel 10 feet in diameter; revolu- 
tions per minute are 125. 

3.1416 

10 diameter of wheel 



31.4160 

125 revolutions 



1570800 
628320 
314160 



feet per minute 3927.0000 this will make 3927 feet per minute. 

Rule to get the area of any stay under one inch: 

We will take J stay; we will get the area the quickest 

way. 

.7854 

8 49 square the seven 7 

8 7 

— 70686 — 

64 31416 49 



64)38.4S46(.6013 area of | stay 
384 

84 
64 

206 
192 



110 'MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to find the inside diameter of a cylinder 

with 22 bolts in cylinder head six and a half inches 

apart, allowing 2| inches on each side of cylinder 

head to be taken off; constant 3.1416. 

22 number of both 
6 . 5 apart 

110 
132 



3.1416)143.00000(45.5 
125664 



45.5 



173460 ' 5. off of each side 
151780 



40.5 

162800 diameter of cyhnder 40 . 5 

157080 



Rule to find how many pounds of coal and how 

many tons of coal a boiler will burn in 24 hours, 

allowing 2000 pounds to a ton, with 75 square feet 

of grate surface, 15 pounds of coal to square foot of 

grate. 

75 grate 

15 pounds square foot 

375 
75 

1125 
24 one day 

4500 
2250 



2000)27000.0(13.5 tons in 24 hours 
2000 

7000 
6000 

10000 
10000 



MARINE AND STATIONARY ENGINEERS CATECHISM 111 

Rule to jSnd how many bolts, 1 J inches in diameter, 
are required for a cylinder cover 56 inches in diam- 
eter, the steam pressure being 90 pounds per 
square inch, the working strain on the bolts not 
to exceed 2000 pounds per square inch. 



56 X 56 X .7854 X 90 
1.5 X 1.5 X .7854 X 2000^ 

56 diameter of cylinder 
56 



62 bolts, say 63 bolts 



336 

280 



1 . 5 diameter of bolt 
1.5 



3136 

.7854 

12544 
15680 
25088 
21952 



75 
15 

225 



2463.0144 

90 steam 

221671.2960 

3534)221671 . 0(62 . 7 nearly 63 
21204 bolts 



.7854 
2.25 square feet 



39270 
15708 
15708 

1.767150 

2000 

3534.300000 



9631 
7068 

25630 

24738 



112 MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to find the number of bolts, when the diameter 
of the bolt and the pitch are given; may be found 
by the following rule: The diameter of the cylinder 
cover is 33 inches, the centre of the bolts from 
edge of cylinder is IJ inches from edge, the pitch 
of the bolts is SJ inches. How many bolts will be 
required in cylinder cover? 

33 — (1| X 2) = 30 diameter of cover. 

30 X 3.1416 

3.25 pitch of bolt 
1.5 33 

2 3.0 

3.0 30 . diameter of cover 

3.1416 

30 diameter of cover 



pitch 3.25)94.248.0(28.9 number of bolts, say 29 holts 
650 

2924 
2600 



3248 
2925 



It will take 29 bolts in this cylinder cover. 



MARINE AND STATIONARY ENGINEERS CATECHISM 113 

Rule to find the indicated horse-power required 
to exert a given thrust or power on a thrust 
block may be found by the following example: 
What indicated horse-power would be required to 
exert a force or thrust of 27,500 pounds on a thrust 
block with a screw propeller of 20 feet pitch, making 
60 revolutions per minute, allowing 33,000 one 
horse-power if the slip be 10 per cent.? 

27500 X 20 pitch X 60 rev. ,„„„ , 

^ = 1000 horse-power 

oo,00U 

1000 X 10 slip ,__ , , ^, ^ „ 
-^ = 100 horse-power and the power actually 

employed will be 1000 — 100 = 900 horse-power 
The horse-power would be 900. 



114 MARINE AND STATIONARY ENGINEERS CATECHISM 



Rule to find the pressure per square inch of 
steam on a piston by the indicated horse-power of 
an engine. Indicated horse-power of an engine is 
180, the diameter of the cyKnder is 17 inches, 
length of stroke is 2 feet, and the number of revolu- 
tions per minute are 80. What is the pressure on 
the piston per pound per square inch? 

17 diameter of cylinder 
17 diameter of cylinder 



180 horse-power ■ 

33000 119 
17 




540000 -— 
540 289 

7854 


2 stroke 
2 stroke 

4 

80 revolutions 

320 


72633)5940000(81 . 7 pounds 

581064 1156 
1445 


129360 2312 
72633 2023 


567270 226.9806 
508431 320 stro] 


ke in feet 


45396120 
6809418 





72633.7920 
Pressure per square inch on piston is 81 . 7. 



MARINE AND STATIONARY ENGINEERS CATECHISM 115 

Rule to find the required time to pump a given 
quantity of water, when two or more pumps of 
different sizes are employed to empty a tank, may 
be found by the following example: Divide the 
product of the time in which each pump will sepa- 
rately empty the tank by the sum of the time 
required by each pump to separately empty the 
tank. The water-ballast pump will empty a tank 
in 3 hours, and the boiler pump will empty it in 
10 hours. In what time can the tank be emptied by 
both pumps working together? 

^ „ = 2 hours and 18 minutes. 

13)30(2 hours and 18 minutes takes to empty 
26 tank 

4 

60 one hour 

13)240(18 minutes 
13 

110 
104 



116 MARINE AND STATIONARY ENGINEERS CATECHISM 




An evaporator is a vessel in the form of a vertical 
boiler in which there are two manifolds connected 
together by a number of copper pipe-coils. The 
upper manifold is connected to the auxiliary steam 
line, the bottom manifold is connected to a steam 
trap and to the condenser, the evaporator is partly 
filled with water, and live steam is admitted to the 
upper manifold and passes through the coils and 



MARINE AND STATIONARY ENGINEERS CATECHISM 117 

bottom manifold and into the steam trap; the hot 
steam in the coils evaporates the surrounding water 
into steam and is then allowed to pass into the con- 
denser through a pipe connected at the top of the 
evaporator, and, after being condensed, is used as 
fresh water, to put in the main boilers. 

Rule to Find the Horse-power. 

Rule to find the horse-power it will take to run 
a number of incandescent electric lights 16 candle 
power, allowing 3 J watts to a candle power, and 
1000 watts is equal to 1| horse-power. We will 
take 1000 lamps, 16 candle power. What size engine 
will it take to run 1000 lamps allowing 3J to candle 
power? Example: 

Add 10 per 16 candle power lamp 
cent, to the 3.5 watts to a candle power 

horse-power 

for friction. 80 

48 

56.0 watts to a 16 candle power lamp 
1000 lamps 16 candle power each 

Lamps 1000)56000.0(56 total watts, this is 56 Kilowatt 
5000 machine 

6000 1^ horse equal 1000 watts. 

6000 

56 

181 

75 horse-power 

7 percentage ' 74f we would say 75 horse- 

— power 

82 horse-power, best to say 90 horse-power 

If you had 200 volts and wanted to find what 
amperage you ought to have, then 56,000 watts 
-^ 200 = 280 amperes. 



118 MARINE AND STATIONARY ENGINEERS CATECHISM 

Rule to find the bursting pressure of a boiler, 
assuming the heads of the boiler are equally as strong 
as the shell of the boiler: Diameter of the boiler 
72 inches, thickness of the plate 13^ = . 4375, tensile 
strength of the plate is 55,000, allowing 70 per cent, 
strength of the seam. 

55,000 X .4375 X 70 
Radius of boiler 

. 4375 thickness 

55000 tensile strength 



21875000 

21875 



24062.5000 

, 70 strength of seam 



half diameter of boiler 36) 16843 . 750000(467 . 88 bursting 
144 pressure 

244 
216 

283 
252 

317 

288 

295 

288 



MARINE AND STATIONARY ENGINEERS CATECHISM 119 

Rule to find the working- pressure when you get 
the bursting pressure of a boiler, assuming the 
heads of the boiler are equally as strong as the shell 
of the boiler : Diameter of the boiler 72 inches, thick- 
ness of the plate j-q = .4375, tensile strength of the 
plate is 55,000, allowing 70 per cent, strength of 
the seam, factor safety ^. 

55,000 X .4375 X .70 
36 X 5 

.4375 

55000 T. S. 



36 half boiler 21875000 
5 factor safety 21875 



180 24062.5000 

. 70 strength at seam 



180)16843.750000(93.57 safe working pressure 
1620 

643 
540 

1037 
900 

1375 
1260 



120 MARINE AND STATIONARY ENGINEERS CATECHISM 

What is the proper diameter of the feed pipe in 
inches of an engine whose nominal horse-power is 
140, constant multiplier .04, constant to be added 3? 

140 

.04 constant multiplier 

5.60 - 

3 constant to be added 

take square root 8 . 60(2 . 93 diameter of pipe 
4 

49)460 
441 

583)1900 
1749 



What is the proper area of the injection pipe in 
square inches of an engine whose nominal horse- 
power is 140, constant multiplier .069, constant to 
be added 2.81? 

140 
.069 constant multiplier 

1260 
840 



9.660 

2.81 constant to be added 



answer 12 . 470 area of pipe 



MARINE AND STATIONARY ENGINEERS CATECHISM 121 

To find the proper diameter of an air pump. 
Rule: Multiply the diameter of the cylinder in 
inches by .6. Example: Let 40 inches be diameter 
of the cylinder then 40 inches X .6 = 24.0; which is 
the proper diameter of the air pump on this engine. 

40 diameter of cylinder 
.6 

24 . inches diameter of air pump 

To find the proper diameter of a crank-pin journal: 
Multiply the diameter of the cylinder in inches by 
.142. Example: Diameter of cylinder 40 inches X 
.142 = 5.680, the proper diameter of crank pin. 

. 142 constant 
40 diameter of cylinder 

5 . 680 diameter of crank pin 

To find the proper length of crank pin by diameter 
of the cylinder. 

Example: Diameter of cylinder is 40 inches X .16 
= 6.40 is length crank pin. 

.16 
40 diameter of cylinder 

6 . 40 length of crank pin in inches 



122 MARINE AND STATIONARY ENGINEERS CATECHISM 

To find the proper diameter of a piston rod by 
the diameter of the cyHnder: Let the diameter of 
the cyHnder be 40 inches -7- 10 equal diameter of 
the piston rod. 

10)40 (4 diameter of piston rod 
40 



INDEX 



Page 3. To find diameter, circumference, and area of a circle. 

" 4. Miscellaneous. 

" 5. To reduce vulgar fraction to a decimal fraction. 

" 6. Cube root. 

" 6. Proportion, 

" 7. Examples on proportion. 

" 8. Square root. 

" 9. Practical questions. 

" 10. Practical questions. 

" 11. Practical questions. 

" 12. Practical questions. 

" 13. To find the tensile strength of a boiler plate. 

" 14. To find the tensile strength of a boiler plate. 

" 14. What advantage does steel have over iron? 

" 15. Practical questions. 

" 16. Practical questions. 

" 17. Practical questions. 

" 17. Explain thermometer. 

" 17. Practical questions. 

" 18. What is a jet condenser? 

" 18. Corliss engine. 

" 19. Corhss engine. 

" 19. Solinometer. 

" 20. Solinometer. 

" 21. To explain indicator and explain the card. 

" 22. To explain indicator and explain the card. 

" 23. To explain indicator and explain the card. 

" 24. To explain indicator and explain the card. 

" 24. Practical questions. 

" 25. Practical questions. 

" 26. Practical questions. 

" 27. Practical questions. 

" 28. Practical questions. 

" 29. Practical questions. 



124 INDEX 

Page 30. Practical questions. 
" 31. Practical questions. 
" 32. Practical questipns. 
" 33. Practical questions. 
" 34. Practical questions. 
" 35. Practical questions. 
" 36. Practical questions. 
" 36. Dynamo electric questions. 
" 37. Dynamo electric questions. 
" 38. Dynamo electric questions. 
" 39. Dynamo electric questions. 
" 40. Starting and charging an ammonia plant. 
" 41. Starting and charging an ammonia plant. 
" 42. Starting and charging an ammonia plant. 
" 42. Practical questions. 
" 43. Practical questions. 
" 43. The question is often asked: Why is it necessary to 

make the longitudinal seam so much stronger than 

the transverse or girth seam? 
" 44. The question is often asked: Why is it necessary to 

make the longitudinal seam so much stronger than 

the transverse or girth seam? 
" 44. To find the amount of water discharged through a 

pipe. 
" 45. Rule to change the water end on a pump. 
" 46. To find the number of gallons a pump will pump. 
" 47. Donkey pump: to find the pressure it will pump 

against. 
" 47. Take the same pump to find the height it will pump. 
" 48. To find the horse-power of a pump. 
" 49. Donkey-pump rule. 
" 49. What is the horse-power of a boiler. 
" 50. Rule to find the thickness of a casting when you have 

the inside diameter and steam pressure. 
" 50. To find the pressure on a guide slipper. 
" 51. To find the pressure on crank pin. 
" 51. To find the pressure on a thrust bearing. 
" 52. To find the speed of a side-wheel steamer. 
" 52. To find the speed of a ship. 
" 53. To find the speed of a ship. 



Page 55. 




56. 




57. 




58. 




58, 




58, 




59. 




60. 




61. 




62. 




63. 




64. 




65. 




66. 




67. 



INDEX 125 

To find the speed of a ship. 

To find the pitch of a wheel. 

To find how many knots a ship will make. 

To find the slip of a wheel. 

To find the slip of a wheel. 

To find the pressure on a piston. 

Engine counter. 

Safety valve. 

Safety valve. 

Safety valve. 

Rule for round tank. 

Rule for round tank. 

Square tank. 

Rule for round tank. 

Rule for round tank. 

68. Rule for round tank. 

69. To find the number of stays to put in fiat-bottom 

boiler. 

70. To find the steam pressure on flat-bottom boiler. 

71. To find the working pressure on round boiler. 

71. Corrugated furnace. 

72. To find the number of rivets to hold steam dome 

down. 

73. To find the size of a safety valve to place on a boiler 

by the square feet of grate surface. 

74. To find the pitch of staybolts. 

74. To find the thickness of plate in a boiler. 

75. To find the pitch of stays in a boiler. 

76. To find the working pressure on triple-riveted boiler. 

77. To find the working pressure on triple-riveted boiler. 

78. To find the diameter of any stay. 

79. To find the steam pressure you would allow on a stay. 

80. To find the steam pressure you would allow on a stay. 

81. To find the number of stays to put in flat surface. 

82. To find the number of square inches over the tubes 

in a Scotch boiler. 

83. To find the working pressure on straight furnace. 

83. Convex and concave heads. 

84. To find the working pressure by the seam of a boiler. 

85. To find the tensile strength of a boiler. 



126 INDEX 



85. To find the diameter of a boiler, 

86. Rule to brace the head of a boiler. 

87. Rule to brace the head of a boiler. 

88. The quickest way to get the horse-power of a boiler. 

89. Rule to find the correct pitch of a rivet single- 

riveted. 

90. Rule to find the correct pitch of a double-staggered 

rivet. 

91. To find the coal burned per pounds per horse-power. 

92. To find the working pressure on straight furnace. 

93. To find the lift of a valve. 

93. To find the percentage of ashes from coal burned. 

94. Coal bunkers. 

95. Coal bunkers. 

96. Coal bunkers. 

97. Coal bunkers. 

98. To find the weight to be placed on the end of a 

lever to balance a weight on the opposite end of 
lever. 

99. To find the stroke of an air pump. 
100. To point off an indicator card. 

100. To find the pressure on piston when speed is reduced. 

101. To find the total pressure in pounds or tons on a 

shaft. 

102. To find the thickness of a corrugated furnace. 

102. To find the weight of a safety ball. 

103. To find the area of any circle without using .7854. 

103. To find the diameter of shaft of a compound engine. 

104. To find the diameter of steam pipe when you have 

the horse-power. 

104. To find how many times the steam expands in 

compound engine or triple-expansion engine. 

105. To find the pressure on a blow-off cock when it is 

under water. 

105. To find the number of gallons of oil in a barrel. 

106. The question is asked: What is steel? 

106. The question is asked: What is alloy? 

107. Rule to find the diameter of a cylinder. 

108. Rule to find the area and the diameter of a circle. 
108. Rule to find the horse-power of a dynamo. 



INDEX 127 

Page 109. To find the limit speed on stationary engine driving- 
wheel. 
" 109. Rule to find the area of any stay under one inch. 
" 110. Rule to find the inside diameter of a cylinder when 

you have the number of bolts and the distance 

apart. 
" 110. Rule to find how many pounds of coal and how 

many tons of coal a boiler will burn in 24 hours. 
" 111. To find the number of bolts to put in cylinder head. 
" 112. To find the number of bolts, when the diameter of 

the bolt and the pitch is given, to put in cylinder 

cover. 
" 113. To find the indicated horse-power exerted on truss 

block. 
" 114. Rule to find the pressure per square inch of steam 

on a piston by the indicated horse-power. 
" 115. Rule to find the required time to pump a given 

quantity of water when two or more pumps of 

different sizes are employed to empty a tank. 
" 116. To explain an evaporator. 
" 117. Rule to find the horse-power of an engine to run a 

number of incandescent electric lights. 
" 118. To find the bursting pressure of a boiler, assuming 

the heads of the boiler are equally as strong as the 

shell. 
" 119. To find the working pressure when you have burst- 
ing pressure on a boiler. 
" 120. Proper diameter of feed pipe from horse-power of 

an engine. 
" 120. Proper diameter of injection pipe from horse-power 

of an engine. 
" 121. To find the diameter of air pump by diameter of 

the cylinder. 
" 121. To find the diameter of crank pin by diameter of 

cylinder. 
" 121. To find the length of crank pin by the diameter of 

cylinder. 
" 122. To find the diameter of the piston rod by diameter 

of cylinder. 



